I've only grown one Renanthopsis in my life and that was Rnthps Elaine Noa (if I remember the name correctly) . I grew it from thumb-pot size in 1967 and bloomed it 4 years later with 32 blooms on a spike with 2 side branches. About 8 months later it bloomed again but with around 20 flowers on one side branch and it wasn't doing very well at all. Actually all my plants at the time were suffering badly from neglect as I had some problems at the time. Soon after I disposed off my whole collection to another collector. To come to the point.... the Rnthps was grown under strap-leaved vanda conditions in a wooden basket in fir bark.
Renanthopsis are very difficult to grow and there are not many of them around....more's the pity.