When notarizing an affidavit, make sure the signer appears before you in person. Given under my hand and notarial seal this day of.A.D.. My commission expires. What do I need first? Everything you need to know about notarizing affidavits. Learn what an affidavit is and how to notarize it. Signature: The affiant must sign the affidavit in the presence of a notary public or another authorized official. The signature should be dated. A notarized affidavit is a written statement that is sworn under oath. Just click one of the links below to download or print our blank forms and legal documents.