The helicopter had been parked adjacent to a refuelling platform 60 millimetres high. As the pilot was bringing the aircraft to the hover prior to take-off the right skid contacted the platform. The pilot attempted to correct with cyclic but the helicopter rolled to the right and came to rest on its right side near the platform. The contact between the skid and the edge of the platform had induced dynamic rollover. The pilot had evidently not identified the problem in time to take the appropriate corrective action of lowering the collective control in order to place both skids on the ground.