I am competent to testify as to the matters set forth herein and if called as a witness would testify as set forth below. Sign your full name on the signature line (see (f) in Sample Form 25).BEFORE ME, the undersigned Notary,. In this lesson, you will learn what an affidavit is and how to format one. You'll also review a sample template that can be used to construct an affidavit.