You can create portable document format, or PDF, files using the Adobe Acrobat software application. If you want to add authentication to a PDF form that you are working with, you can add a digital signature field to the file. The field consists of a text box that you can sign to show that you created the document, or you can also use the field to have others sign the document, if necessary. For example, you can add your initials to the document as your signature.
