I'm searching for a replacement for Rising Gallery 100, smooth , not vellum.
I understand the paper is no longer being made. The weight, tooth and size were perfect for what I do. Can anybody with experience with this paper make a recommendation for a substitute?

Coventry Rag Smooth is as close a substitute as exists. It's available in a range of weights and sizes:
www.legionpaper.com/coventry-rag

I hope this helps.