Power of Attorney – Agent signing

If you have Power of Attorney for someone and you have to sign a document for them, do you sign the person's name or your own as PofA?

You should sign the agents name and state yoru name and that you are signing in the capacity as agent under a durable power of attorney. Signing there name without indicating that you are signing as agent is not generally advisable. Many agents sign and then for space limitation reasons indicate "as POA".