The general rule is that a contract is effective when both parties agree (ie, sign the Agreement of Sale) AND acceptance is communicated to the offering party. PAR's Buyer Agency Contract includes all of the legallyrequired language and allows for a buyer's broker fee to be structured in several ways.This is going to be how to fill out the agreement of sale for pennsylvania. First, the buyer must present a valid offer, in writing, to the seller. Second, the seller must accept the buyer's offer to purchase the agreement. Your offer must be in writing. This is done through a Residential Purchase Agreement, which must conform to varying state and local laws. The agreement of sale is strictly who's on first what's on second who are the players and that's what we're going to identify here.