It’s from a tickling magazine published around 1985. I can’t recall the title, but it contained at least 2 pictorial stories, one F/F & one M/F. Published by HOM, I believe.
I think this was among the very first scanned photos I ever saw on the internet. I can't remember the name of that early site but it had pages of images, divided by body part; feet, armpits, etc.