You are the beneficiary, and the Petitioner is Bxxx Cxxx. Both need to sign Form G-28. Form G-28 is a form that authorizes the law firm to represent you in the proceeding before the Immigration Service in connection to the H-1B case. You are the Beneficiary, and you need to sign one. The petitioner is Bxxx Cxxx, and they need to sign one as well.