Ral Yekkiv was a Rebel and an associate of Roger Stern. He met with a group of rebels on Greyman's Planet when they came to meet with Stern. Unfortunately Stern had been captured by the Empire, though he told the group to continue with their mission to get supplies and transport them to Karinda Outpost, as he was taking care of freeing Stern himself.
Sources
"Milk Run" — Polyhedron 83 (reprinted in Polyhedron 83) (reprinted in Polyhedron 83) (reprinted in Polyhedron 83) (Unlicensed)