Before starting this get the tools to do the job. Forget the spray can, that's a nightmare you don't need.
Start with these items.
http://www.amazon.com/gp/product/B00578QW70?*Version*=1&*entries*=0
http://www.amazon.com/Dremel-9905-Tungst...ords=dremel+bur
http://www.amazon.com/gp/product/B000HI690U?*Version*=1&*entries*=0
http://www.amazon.com/Dupli-Color-DAP169...+etching+primer
http://www.amazon.com/Feather-Hi-Stainle...ge+razor+blades
http://www.amazon.com/Mothers-08224-Cali...r+care+products
http://www.paintscratch.com/
Order or get from a local auto body supplier touch up paint that is single stage or base clear mix not separate base/clear, they may have some of the other items also, HD has dremel bits. The rust mort is a qt and will probably last a life time but its worth it.
Start by removing the rust and removing any lifting paint with the mini bur, work carefully not to enlarge the spot too much, get it perfectly clean and rust free then wipe it down with IPA.
Use a mini applicator to apply a small amount of rust mort to the spot, don't blob it on just wipe it on the metal then leave it overnight.
Wipe with IPA then spray a little self etching primer into a small cup (i spray it in the lid), use another applicator so apply a single thin coat.
Now for the fun part. Use a applicator (not the brush in the bottle and apply a single thin coat, let dry a couple of hours and repeat a few times over a few days if necessary until the paint is raised above the other paint.
Let the paint cure a few days then spray a little detailer on the area, take the double sided razor blade and lay it flat on the paint in front of the repair. Holding the blade on the sides just wiggle it through the raised paint, it will now be level with the rest of the paint.
Scuff it very lightly with 3000 paper carefully and polish.
I used Amazon just to show the product, you can get this stuff anywhere. Rut Mort brand is the best, there is no substitute.
The self etch primer works great and dries fast, just be sure to turn the can over and spray it till the nozzle clears after use or it will plug the tube in short order.
This is time consuming but with a little practice gives fantastic results that will last the life of the rest of the paint without rusting.
I use this on paint chips and deep scratches so effectively that they disappear but i have a lot of practice. I suggest practicing on some old panel first, you will get great results in no time once you get the feel for it.
This is a common body shop method AKA cut and buff, i use a tungsten block instead of a razor, always use a fresh side of the blade for every spot they dull fast and will pull on the repair, the tungsten doesn't dull but a small block is about $100.
