5. A chartered real estate agent’s certificate, provided for in paragraph 4 of section 1, may be issued only to a natural person. A holder of that certificate may use the title of chartered real estate agent but may engage in a brokerage transaction referred to in section 1 of the Act only if he is employed by the holder of a chartered real estate broker’s certificate or by a multidisciplinary firm holding a certificate provided for in any of paragraphs 5 to 10 of section 1 of the Regulation respecting multidisciplinary firms, or if he is authorized to act on behalf of the holder of such a certificate. A holder of that certificate may not employ the holder of a real estate broker’s or agent’s certificate or authorize such a person to act on his behalf.