A little rust that turned into a lot

[wrfdff4]

A couple months ago I noticed a little rust spot on the lip of the fender wall on my Grand Prix I pick away at the paint and a little spot turn into a problem that I couldnt see well its not to noticeable where I need to take it to a shop so first I sanded it all off so theres just bare metal next should I just put touch up paint on it ?
Thanks,
Bobby

[Mid-Life Cruiser]

First,

However, now that you are to bare metal, before you add touch up paint, you will need some primer. If it is not that noticable, prime and touch up. There are plenty of threads regarding touch up techinques. Most all are dependent on the nature of the touch up (location and size are usually the most significant variables).

Good Luck!