Using Rheostats for first time

My main question with using rheostats is where do you take your temp from when setting the dimmer? Do you take the temp from the UTH itself, the glass or on top of the substrate?

Either directly on the UTH, or on the glass below the substrate where the UTH is. You want to measure the hottest point, just in case your snake burrows, and so he/she doesn't move the probe.

My Thermostat probe is wedged between the malemine and the UTH.

That's what I thought. Thanks a lot

So I took the temps of only one of my tanks as my other is mid shed and I obviously didn't want to bother him. Removed substrate, placed probe to find that max temp was at about 103. Set up the rheostat to get it down to 94 and called it good. Just out of curiousity, could that extra 9 degree's have been an issue for anything? I'm just trying to justify me adding that piece of equipment. I guess the real perk of it will kick in in the summer when I have to drop the temp big time.