I'm with Squilliam ... rather than trying to create a new finish, which won't match the rest of the knife, trying to match the finish of the knife with sand paper would probably be easiest. I'd start around 320 grit (which will remove the marking pretty quickly) and then move up until you've got a match with the finish of the rest of the knife (likely around 400-600). As Squilliam mentioned, it is important to match the direction of the existing satin finish. If you start out creating swirls, they will be very hard to get rid of. If you're worried about the sandpaper, you might try a buff stick. These look a lot like the buff sticks that are used for nails, but are designed for metals. It gives you three grits of increasing smoothness, which allows you to fix small imperfections or do projects like this. I find they can be a little easier to manage the direction of the satin finish.
-daniel