In a power of attorney situation, you must obtain a copy of the power of attorney document and keep it in your file. You should request a copy of the power of attorney document and keep as a part of your record.Signing Requirements. A power of attorney in Pennsylvania requires the signatures of two witnesses and a notary public. When it comes to selling a house under a Power of Attorney, the authority to do so depends on the specific powers granted within the document. You may select any competent adult to act as your agent. A Pennsylvania Power of Attorney (PoA) is a legal document that grants a trusted individual permission to handle legal and financial affairs for you. Use a power of attorney for real estate form to give someone the authority to buy, sell, or conduct any other business involving real estate that you own.