How to Add Digital Signature in PDF in Mac: A Complete Guide
By adding a digital signature to a PDF on a Mac you can speed up, simplify and make document-based workflows easier to manage. macOS provides built-in tools for adding a simple signature to any PDF document, be it a business agreement, application form, invoice, declaration, or any other PDF document.
If you want to know how to add a digital signature in PDF on Mac. This guide explores the many ways to add a signature to a PDF on Mac, when to use each method, and how to make sure your signed document is suitable for its intended purpose.
What Is a Digital Signature in a PDF?
A digital signature is a way of establishing the identity of a signer and helping to verify the integrity of a digitally signed document. Electronic signatures, based on certificates, use cryptographic technology and a digital certificate to link a signature to a particular signer.
If an organization has to sign a lot of documents, then it can better organize this process by using special signing software. E.g. eChaap is designed to facilitate digital signing by using signing dongles and it can track signed documents with timestamps. Also, its stand-alone version can support multiple documents, multiple signatures and signer logs.
How to Add a Signature to a PDF on Mac Using Preview?
If all you need is to add a signature to a PDF on Mac, one of the easiest options is Apple's built-in Preview application.
Step 1: Open PDF with Preview
Locate the PDF file on your Mac and open it with Preview.
If you have another app set to open PDFs by default, right-click the file and choose Open With, then choose Preview.
Step 2: Open the Markup Toolbar
Open the PDF and head to the Markup toolbar.
Use the markup option in the toolbar to access tools for adding annotations, text, shapes and signatures.
Step 3: Select Signature Tool
Tap the Sign or Signature icon in the Markup toolbar.
Depending on your Mac and macOS version, you are able to create a signature in Preview with supported input methods, such as the trackpad or camera.
Step 4: Signing Your Signature
If you've never created a signature before, Preview will walk you through it.
You can use your finger to write a signature on the trackpad. On supported devices, you can also use the camera to capture a handwritten signature from a piece of paper.
Preview can save your signature for future use once created.
Step 5: Add Signature to PDF
Select your saved signature and click where you want it.
The signature can normally be sized and positioned to fit correctly within the space provided for the signature.
Step 6: Save the Signed PDF File
Sign the PDF and then save it.
If you want the original unsigned document, you might want to try Save As or copy another one.
How to Add a Certificate-Based Digital Signature to a PDF on Mac
If you need a certificate-based digital signature, that's a different process than adding a signature image.
Generally you will need:
Valid Digital Signature Certificate
The credentials or certificate used for signing
Compatible digital signature software
Access to a signing mechanism or certificate
Sign PDF
The signing software may access the certificate via a compatible device or digital-signing environment, depending on the certificate and signing configuration.
This may vary depending on the actual process, as different DSC providers, certificates and operating systems may have different requirements. If you run a business that signs a lot of documents, having a dedicated digital-signature app can make your life easier like Eklavya's eChaap .
How to Add Multiple Digital Signatures to a PDF on Mac
Certain documents require signatures from multiple people, for example a contract may require signatures from a manager, authorized representative and client. If the signing workflow includes multiple signers, the document can be prepared for the signers that are required. But the order and manner in which you sign can be important.
And do not think that it is enough to add a signature, and then modify the PDF at will, to keep valid an earlier signature based on a certificate. Changes made after signing may affect signature validation.
How to Verify a Digitally Signed PDF on Mac
Verification is an important step after learning to sign a PDF on Mac.
Open the signed PDF in a PDF reader that supports signatures and verify the signature information. Based on the software and certificate you can see the signer, certificate information, signature status and if the document was modified after it was signed.
A valid signature is not simply a signature graphic on the page. Don't just look at what the signature looks like for important business or official documents. Use a PDF signing or verification software that supports this signature to check its status.
Common Problems When Adding a Digital Signature on Mac
Missing Option to Sign
If you don't see the option for a signature in Preview, make sure that you have the Markup toolbar turned on, and that you're using a PDF that can be marked up.
PDF Is Password Protected
A PDF that is locked may not allow you to edit or annotate. You may have to ask for permission or find the right password before you can add a signature.
Signature of Recipient Rejected
This can occur if a recipient needs a digital signature based on a certificate, but the PDF has only a visual signature.
Check the exact signing requirement and, if necessary, use an acceptable DSC-based signing method.
The Digital Signature Is Invalid
Changing a signed, certificate-based PDF may cause the signature to not validate as expected. Ensure that you finish the document before applying the final digital signature.
Digital signature solutions may also benefit companies that process large volumes of digitally signed documents to help streamline signing, document management and related workflows.
Best Practices for Adding a Digital Signature to PDF on Mac
Remember these practices for adding a Digital Signature to PDF on Mac.
Make sure you read the PDF before you sign.
Do not sign the original document.
Make sure you know whether you require an electronic or certificate-based signature.
When requesting a DSC specifically, use a valid digital certificate.
Do not modify a PDF that has been signed with a certificate unless the workflow permits this.
Verify and approve the final signature before sending the document.
Keep your signed documents safe.
Monitor key signed documents and signing events.
Use trusted signing software and protect your digital certificate credentials.
Final Thoughts
Learning how to add digital signatures in PDF on Mac is easy once you know which signature you need.
If you're looking to create a simple electronic signature, Preview offers a handy way to create and insert a signature directly on a PDF. But when a document has to be authenticated through a Digital Signature Certificate, there is a need for a signing process based on the certificate and not just an image or a signature drawn.
Always check the requirements of the recipient before signing and keep an original copy and check the finished document carefully. Dedicated digital-signature solutions may provide further capabilities for document signing, tracking and managing signatures, which may be important for organizations handling multiple documents or complex signing workflows.
Frequently Asked Questions
To add a digital signature to a PDF you can use Apple's Preview application. However, if a certificate or DSC is to be used to digitally sign a document, then digital signing software and a valid certificate that are compatible may be required.
No. A signature pasted in using Preview should not be automatically considered the equivalent of a certificate-based digital signature. The right way to sign depends on the document, who it is for and what is required.