I’ve never owned a Nikon RF, but as I understand it the F is basically an SLR version of the SP. In fact if I’m not mistaken, some very early Fs(like the first couple hundred made, or maybe not that many) had cloth SP curtains. In turn, some late SPs had metal F curtains.
The F and I think also the SP follow the shutter button placement of Barnack Leicas with the button toward the rear of the top plate. The rotating shutter collar to set rewind is also Barnack.
Of course Leica by that time has moved to the shutter in the rewind pivot with the M3 and M2.
I think in this side discussion, it’s worth mentioning that there’s no one single innovative feature in the F. With that said, it was an innovative camera by combining a bunch of features from elsewhere(instant return mirror, automatic aperture, interchangeable finders, provisions for coupled metering, and a few others I’m forgetting) into a single camera and, probably more importantly, offering a full system from the beginning. By 1960, they’d covered 21mm to 300mm in rectilinear(plus an 8mm fisheye somewhere along the way), macro, and some other special purpose uses. That’s what made it such a game changing camera.
I’ll also mention that I will take a Canon Barnack clone over a real Leica Barnack any day. If the Leica IIIc was my only interaction with the brand, I’d not own another, and I’m hard pressed to think of a way a Canon IVs isn’t better. The M3 and subsequent M cameras are a different story, although the Canon 7 is a worthy match in a lot of ways. The 7 is the only RF I’ve been personally owned that combines a huge number of frame lines with the ability to only display one at a time…