After my dk green River Rock disaster (3 coats, still terrible roller lap marks)I gave up. Went to my local independent HW store (Fischer's Springfield, VA) with an EXCELLENT paint dept. They told me they often get people asking how to paint over the River Rock (they don't sell it). "We never saw those problems until Glidden started making it instead of Sherman-Williams."
Anyway, they custom mixed a color of Martin Senour interior latex (Williamsburg collection). No computer match, they just picked a near-matching color, adjusted the tint, and when they dabbed & dried it over my RL chip I couldn't even see the dab, it matched so perfectly.
Took it home, rolled 1 coat over the River Rock, and while it looked streaky wet it dried to a perfect, even, flat, (did I already say perfect?) wall that retained some of the sand texture. Phew! What a relief!
Those that blamed all the problems on poor technique should not...GOOD paint is extremely forgiving.
By the way, it was $17.95 per gal. I had used 4 gal of RL, I used 1 gal of MS.