A POA in Pennsylvania must be dated, signed by the principal, witnessed by two adults, and notarized. If the principal is not able to write, he or she may sign by making a mark (such as an “X”) or by directing another person to sign on his or her behalf. If this is done, there must be two adult witnesses to the signature. The notary public may not be the agent. The witness requirements for a power of attorney in Pennsylvania are that a witness must be at least 18 years of age, but may not be the agent or a person who signed the POA on behalf of the principal.