apply the touchup in several layers, ie.......build it up above the original paint, let dry for a while, then take a sanding pen and spot sand the touchup paint. you can use soap and water as well if you would like, i never do, but it would be safer, if you are a novice.
then after you get the touch up paint blended in to about the right level of the origanal paint, take some rubbing compound or a nice scratch remover and buff it out a couple of times to get the scratch marks off.
if you have a buffer or porter cable like i do, then even better, just buff the spot out, starting with a harsher compound moving to a lighter compound in stages.
i've done this method many many many times, with great results, you can't even tell there was ever touchup paint there.
good luck