I don’t know who makes the holder for the LRF but it’s clearly just got a pic rail to Arca adapter on the bottom and is attached to the scope rail with a cheap 90° picatinny adapter.
LRI still makes those pic rails that attach to the Hensoldt scopes.
If you want a cage system for a Henny you can get the Badger SLICK or the Cadex Surveillance Kit.
FWIW I used to have a Sig LRF mounted to a spotter in a similar manner and it kinda sucked. The eyepieces end up on different levels so it’s hard to look through one or the other, and the reticles aren’t co-aligned so you have to move the spotter off target to range or move the LRF off target to spot. If you really want to spot and range at the same time you gotta get a LRF intended for weapon mounting like a Raptar, Radius, MARS, Storm, RULR, etc., so you can slave the rangefinder to the reticle in the spotter. I put a Cadex cage on my Spotter 60 and put a RULR on top and it is a far superior setup (at a downside of $6k of expense).