If you have been named as “Attorney in Fact” by the Grantor of a Power of Attorney, you should sign YOUR OWN NAME, followed by the words “Power of Attorney.”
Do NOT sign the Grantor’s name EVER.
By signing your name and the words “Power of Attorney” after your name, the person receiving documents signed by you on behalf of the person who granted you Power of Attorney understands exactly what is being provided.
(You should also provide a copy of the signed Power of Attorney document whenever a contract or agreement is substantial.)
Complete details can be found here on Standard Legal’s Power of Attorney legal forms software.