The pilot of a Rockwell Commander 114 aircraft had completed a short local flight and was operating in the circuit pattern at Maitland. The pilot reported having difficulty sighting some slower traffic ahead. The aircraft subsequently landed with its landing gear retracted, sliding for approximately 130 metres. The pilot and passenger were able to exit the aircraft without assistance. After establishing that it was safe to re-enter the aircraft the pilot & passenger checked that the power and fuel were switched off. At this stage they noted the gear selector was in the down position. Post accident activation of the landing gear alternate extension system successfully lowered the gear. No defect was found with the operating system that would have prevented the landing gear from operating normally. Damage to the underside of the aircraft was consistent with the landing gear being retracted at the time of impact.