To create a digital signature you have to use Adobe Acrobat DC (not a web browser or adobe reader) to open a PDF that requires a digital signature and click on one of the signature blocks as if you were signing the document.
Tip: How Do I Find the BISD Software Center
Tip: Set Adobe Reader DC or Adobe Acrobat DC To Be The Default PDF Viewer
Select Create a new Digital ID
Always choose Save to file:
Enter your Name and Email Address
Leave the other options alone.
Add a 6 character minimum password to protect the digital signature and click Save