Right, to get the best possible result, catch/treat these while they're small.
Using a knife tip, start in the centre of the rust spot, and work outwards - lifting whatever paint has been affected (this should lift off easily). Then carefully chip away at the paint immediately beyond this - you want to get to nice shiny steel, but don't take too much away.
Apply Kurust using a cotton bud - allow to dry for an hour at least.
Then, get a touch-up paint, thin it down slightly, and apply using an open-ended paper clip - don't apply too much in one go, you want to gradually build-up the coats until it is level.
After a couple of days (enough for the paint to cure & set), you can give it a light polish.
It won't look absolutely seamless - but view it as a 'damage-limitation' exercise, and you will be satisfied with the result.
Best of luck, if you need any further advice, just ask away.