If your paint on your frame starts chipping, we recommend touching up the paint to prevent rusting. If it is chipped down to the bare steel, we also recommend applying a primer to the steel.
For the paint itself, Wabi carries some touchup paint of the most recent stock season colors. We offer a touch up kit with paint, a microapplicator and very fine (800) wet sandpaper for $15. However, if the frame is an older frame, we don't typically carry touchup colors. Also, most of our stock paints are not standard colors with a color code (like RAL) so we can't provide a code for match.
We usually recommend having the frame paint matched at an auto paint/specialty paint store. They can usually get an 80%+ match. Even though our paint finishes have a base color coat with a clear top coat, we recommend just getting a single stage enamel in the corresponding finish (ie gloss) to match. That is sufficient for touchup and usually looks better than trying to do a base coat and clear coat. A half pint of single stage paint is usually about $25-30.
If you need primer, we recommend either an enamel or acrylic primer made for bare steel. Given it is just touchup on a small area, don't worry too much about the best option - any primer will work.
When applying primer or paint, we recommend using the minimal amount to cover the chipped area. This means touching a very small amount with a micro applicator until the area is covered. Once the primer or paint is dry, we recommend using either a very fine grit (800) wet sandpaper gently on the area or a polish with a foam spin brush (on a drill). Either way, sand or buff sparingly to just help the touchup blend (but don't expect it to completely go away).
Also, remember to clean the chipped area before applying primer or paint. This means using an appropriate solvent/cleaner and sanding away any rust/bad paint.