The signature of the attorney-in-fact must simply designate that the attorney is acting in a capacity on behalf of the principal.
Most often, the document that the attorney-in-fact will sign already contains the name of the principal.
For instance, if the attorney-in-fact is signing a contract for medical services, the principal’s name will be in the contract.
It must be presumed, then, that the attorney-in-fact is signing for the named principal, making the double-identification redundant.
If you wish to sign as attorney-in-fact as “by [agent’s name] his/her attorney-in-fact,” you are certainly free to do so.
But using the phrase ‘Power of Attorney’ after said signature achieves that same goal, often within the space confines of a legal document.
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