It’s unfortunate that this doesn't work on the RX1R II.
When I set "FINDER/MONITOR" to "Viewfinder (Manual)" and use the custom button, the EVF just stays on the whole time, so eye detection isn't used, which makes the setup pointless.
On the RX1R II, the best option is simply to turn the camera off after taking your photo or series of shots. That saves the most battery life.