I dumped the Leica optical finder for something smaller and supposedly a closer match to the 35mm RX-1 lens focal length. Here’s what it looks like on the camera, with the thumb grip:
The framing accuracy with the OVF is about as good as the accuracy of any RF camera — Leica M series, Nikon S series, etc. — with an auxiliary finder, which is to say, not very good by SLR or EVF standards. The Voigtlander finder appears to be a little tighter than the actual coverage, which is OK by me, considering the amount of slop.
I’m about ready to give up on trying to identify the spot where the camera’s going to focus by looking through the optical finder and guessing where the middle is. Even leaving parallax aside, it’s hard to estimate. I’ll try letting the camera decide where to focus.