@loren@Rheall if you have a stationery store near you, you can bring a sample of the paper scrap & see if there are any permanent gel pens or other permanent pens/markers to try.
Paint pens, like the gold Sakura micron pens, tend to be really uneven and goopy a la correction fluid, and require a lot of practice to get the flow right—not something you want to be worrying about while signing hopefully a bunch of prints, which is why I think metallic permanent marker in an extra fine tip is smart