Well, generally lights work better than reflectors. I would say that 99% of lights do not include any sort of built-in reflector that meets government standards. The laws in many places mandate a reflector. Some creativity may be needed to have both installed. For instance, I have my light installed on the seatpost like your light is, and my reflector is installed on my rear rack. From your photo, you might want to consider turning your light upside down if possible to keep the reflector visible. For best results, try to make the light and reflector perpendicular to the ground for maximal visibility.