For filling in a a ratch I've had better esults with a tin of paint than a pen. I've ordered from paints4u a few times by paint code and it's always been a good match.
If not spraying an area, I use the below method.
Degrease the area with panel wipe
Put some masking tape underneath the scratch to car h any drips
Using a cocktail stick or pin, pick up a drop of paint and fill in the scratch. The less paint the better. Repeat until the paint sits proud.
Using high grit (something like 3000 grit) wet and dry sandpaper soaked in water, lightly sand until the paint is level. Don't worry about the original paint as the paint is much softer than the lawyer and you'll only lightly sand the laquer.
Machine polish with cutting compound. This restores the shine of the original paint and the new paint.
It should look good at this point, but you can degrease again and laquer over the top.