STEP 1- The capability to sign documents digitally with the Mail app was introduced with Mac OS X Yosemite. To start signing PDFs on Mac using Mail, follow the instructions below: You’ve learnt how to create digital signatures in Preview, but there’s a user-friendly way in your Mail app too. Must-Read: How To Add Signatures In Gmail? PART 2- How To Sign Documents In Mail Using Mac? Another workaround to sign PDF on Mac is through using Apple Mail. You can move and resize the signature to suit your needs. This is how you can add signatures using Preview tell and then use it in a PDF. Make sure you are holding the piece of paper steady and your writing matches the guideline. Start by writing a signature on a plain, white paper and then simply holding it up to the webcam. STEP 6- Alternate way to add signs is through the Camera option. Scribbling it on a trackpad using your finger or stylus is the easiest yet quickest way to add signs. STEP 5- Now you have two options to create a Digital Signature To Sign A PDF on Mac.