How to Digitally sign a Adobe PDF Document
Open or create your document in Adobe Acrobat
On the top Left there are tabs, click on Tools
Then, select the option Certificates
Click on Digitally Sign
With your mouse, draw a box where you want the signature to appear. A dialog box will appear which allows you to select Sign As. This will display your Digital ID.
Select your Digital ID
Note: Inside the dialog box, if you would like to check the certificate details, simply click on the View Details.
Click Continue and Click Sign
You will be required to save the document, type a name for your file, and click Save. The file shows a blue bar at the top of the screen indicating that the PDF file is signed.
Note: Acrobat sets the first signature method chosen as the default method of signing. To clear out Digital IDs in Acrobat, select Edit > Preferences > select Signatures on the left side of the screen > click More after Identities & Trusted Certificates > select the relevant Digital ID > click Remove ID > confirm that you want to remove the Digital ID> enter the password > click OK