here's my take on the RNF

I've had several, from 5'4 up to 5'8"

I was told to scale from 6-8 inches shorter and about an inch wider. I got a little scared thinking that was too short (on my first one, this is like ten years ago btw)so I ordered 4 inches shorter.
My normal shortboards were around 6'0 x 18 1/4 at the time, so the 5'8 was 19.5 or so.

The board wasn't as quick as a groveller, but it really caught waves well and had ridiculous amounts of drive and skate. A lot like the feel of the retro fish in that you were on your feet early and already skating. I had the big MR twins in then and that board really excelled in longboard type waves, in other words, too mushy for a shortboard but still clean and lined up was most optimal at around the stomach to shoulder high range.

I switched the fins to some normal, (I think g5), the board gained some snap at the expense of drive and skate, but went slightly better backhand, it would be a bit slidy at times. A few years later I put in the H2 larges and that was when the board performed with the greatest versatility. The cant kept the skate and held well for the carvy roundhouse cutbacks. That's basically what the board did best, trim/skate float and cruisy cutbacks.

Then I got the opportunity to go the other direction. I went for a full on 5'4 (8" shorter) x 19 3/8 x 2 1/4"
this board was best in small punchy waves knee to about stomach, it was a lot quicker, but also a lot less drivy with considerably less skate. It has fins set further back than normal (i'm guessing it was meant to be used as a twin) but because I am scared to put fins that large in a board this small, i tinkered with a lot of other sets until I eventually found the fins that put some more drive and skate back, Webber Curves. I recently started riding this one again and now love it. Like I said, knee to stomach high, and this thing can 'grovel'

I've had and tried a few more, there are some discrepancies in the model with the rail thickness and tail width. I prefer the slimmer tails and rails, otherwise they feel like a bar of soap to me

I've spent some time in Va beach and I guess I'll summarize it like this. If you surf the short peaky stuff at 1st street and Croatan, than go 8" shorter with thinner rails. If you surf the rest of Va beach go only 6" shorter and reap the benefits of the extra paddle when winter wetsuit season rolls around