Rust stain from hammer

My recently college graduated son left a hammer on the vinyl lined steps of our pool. When I found it and removed it this morning it left a nice rust stain. I couldn't remove it with a sponge, would ascorbic acid do the trick?

Thanks and hello to everyone,

Tom

That would be the thing to try.

Well that worked, thank-you!

Tom

Awesome! Now, keep hammers out of your pool! :p