shawn
Veteran
The Ricoh GW-4 has a 49mm thread on it and seems to work well on the x100. No vignetting (it was built for the wider GR3) and it gives a little bit wider FOV than the Fuji teleconverter, just under 26mm FOV. It blocks a lot of the optical viewfinder but since the framelines are wrong anyway the EVF makes more sense.
One thing to watch out for is the threading on the adapter is deep to activate a switch on the Ricoh.
On the x100 this works fine. But I have a IR Chrome filter on my full spectrum x100 and that filter doesn't have a lot of threads available. The GW-4 wouldn't attach to the IR Chrome filter. I bought a cheap 49mm UV filter and took the glass out as a spacer.
With the spacer on the IR Chrome filter the GW-4 attaches fine.
I leave the spacer on all the time. It brings the lens cap just about even with the hood that is normally on the camera.
Shawn
One thing to watch out for is the threading on the adapter is deep to activate a switch on the Ricoh.

On the x100 this works fine. But I have a IR Chrome filter on my full spectrum x100 and that filter doesn't have a lot of threads available. The GW-4 wouldn't attach to the IR Chrome filter. I bought a cheap 49mm UV filter and took the glass out as a spacer.

With the spacer on the IR Chrome filter the GW-4 attaches fine.

I leave the spacer on all the time. It brings the lens cap just about even with the hood that is normally on the camera.
Shawn