Step 1: Open PDF and Click on Tools Menu and then Certificates.
Step 2: Click on Digitally Sign ( As shown below )
Step 3: Draw a rectangle on PDF where to sign.
Step 4: Click on Configure New Digital ID button.
Step 5: Click on Create a new Digital ID and Click on Continue.
Step 6: Click on Save to Windows Certificate Store and click on Continue.
Step 7: Enter the details like name, company name, eMail ID, Country etc and Click on Save.
Step 8: New ID will be created and will be visible. Click on Continue button.
Step 9: Click on Sign button.
Step 10: Select path and save PDF.
Step 11: Digital Signature will be signed.