ORIGINAL: Rodney
If you are using Klass Kote, I believe you can get flat as well as gloss hardner if you do not like a glossy finish. I my book, Klass Kote is the ultimate finish as it is very durable and flexible so that you do not get any problems with unsupported fabric areas. Plus it brushes on well without leaving brush marks if you do not want to spray paint.
Rodney, I'm a number one fan of the Klass Kote. Love the stuff, bullet proof and easy to work with. You can get the matt for it. On a gasser it isn't needed though, you can use water based house paint with a clear poly over the top for the gloss. My only problem with the KK is the price so I only use it on special planes that are sheeted and glassed. I think KK is the best paint for models on the market. I just wish it was cheaper to use.