I just noticed a pretty deep sratch on my car the other day. Not sure what hit it (shopping cart, bicycle handle). It's about 2 inches long, deep, and shows a little rust, and i'm pissed about it. I know for a fact that i noticed it approximately 24 hours after it happened and shocked that rust appeared in that time frame. I have some touch up paint that matches my car. Even though there's a little rust showing (half a penny sized), if i fill it with some touch up paint, will it seal the deal from the rust expanding. It's too minor to take it to a body shop. With no dents or door dings on my ride, i was pretty upset when i noticed it.
yeah tape up around the the scratch. use 400g paper and feather out the edges of the scratch. try not to make the scratch bigger but knock the rust off and smooth out the edges. apply first coat thin and reapply every 15 minutes till even with original paint. Let dry after a few days wet sand to blend then wax.
Touch up sounds a lot easier than it is. My girl does touch up. One of her accounts is subaru if kennesaw. Contact her. It's not very expensive either,but it will blend better than you or I could possibly make it.