More serious rusting can lead to obvious holes in the metalwork, or as often happens in double skinned areas such as rear wheelarches or door bottoms, rust or blisters which appear because the panel has rusted quietly away from the inside. By the time the first signs show, the metal in that area is already beyond help. The only long term repair will involve a panel\section replacement, or if the area is very small and the rest of the panel is absolutely sound, body solder can be used effectively. For a purely cosmetic temporary repair, the affected area can.
