Where a multifamily dwelling development is located in a nonresidential district, one identification sign shall be allowed, provided that the sign shall not exceed 10 square feet in surface area, shall not rise to more than six feet from the ground or sidewalk, and no portion of it shall be set back less than 10 feet from the front lot line. If lighted, it shall be illuminated with a white, steady, stationary light, of reasonable intensity, shielded and directed solely at the sign, not casting light off the premises.