I wouldn't rattle can it. You can treat some of the larger scratches with clear nail polish; one trick is to apply it in small drops with the end of a toothpick. This will help prevent the rust from reappearing once you have treated it. Then I suggest you go to an auto parts store (or well-stocked hardware store) and pick up some Meguire's ScratchX. There's a similar product made by Kit that is less expensive and probably works just as well. Another forum member who I trust suggested Meguire's #2 Fine Cut Cleaner over Scratch X. Any one of these will help to bring the lustre back to the paint, then wax the frame.