Coat Applicatior

I'm not sure if I want to spend the 15 credits to get the horse I want. I wish to have a Seal Brown Roan(RnRn) Gypsy Vanner. If I got the coat applicator, would I be able to do this? Or since the roan is a pattern, is this not possible?

You would need both a coat applicator AND a pattern applicator. A coat applicator only affects the coat color, and a pattern applicator only affects the pattern.

Your other option would be to find a Vanner that already has the RnRn genes, and then use the coat applicator; the coat applicator will not do anything to the pattern genes the horse already has.