A Pennsylvania purchase agreement creates a secured contract for a residential property transaction. First, include the property address as well as its legal description (found on the deed).Then go into detail about what is included or excluded from the sale. A Pennsylvania residential purchase agreement establishes a legal arrangement between a buyer and a seller in a real estate transaction. All done through Google Forms, which is free. View the forms library. Use our library of forms to quickly fill and sign your FSBO Real Estate Listings: Buy or Sell a Home forms online.