Digital signatures are like paper-based signatures, but better because they include encrypted information so you can verify their authenticity.
You can digitally sign a document to securely record the identity of the author, and to verify the content has not changed. Digital signatures in a PDF document can show text, or an image such as a photo or an image of your handwritten signature.
To digitally sign a document:
On the Protect tab, in the Certify Document group, click the arrow under Sign, and select a signature from the gallery. To sign a document, you must first have a digital ID. For more information, see Digital IDs and Manage Digital IDs.
Click on the page where you would like to place your signature
Nitro Pro prompts you to save the PDF file with the digital signature. Click the digital signature to view and confirm its details, and then save your PDF file. For more information, see View and validate certificates and signatures.