Preserving an autograph made with a pen that smudges?

[SnapShots2015]

I've recently received an autograph on photographic paper signed with a gold pen that doesn't dry. The slightest touch and the ink is either removed or smudged.
I was going to store the photo in a polyester pocket along with my collection in an arched lever binder, but I feel the photo may still move slightly when I'm having to make new additions to the binder which will make it smudge more.
Can anyone recommend any techniques to prevent further deterioration of the autograph please?
Many thanks.