You can leave your UHK flat, set up positive tilting (back raised) or tenting (middle part raised).
At this point, we feel obliged to mention that positive tilting is less ergonomical than leaving your keyboard flat because it bends your wrists backwards unnaturally. It's a remnant from the typewriter age that keyboards still support for no ergonomical reason.
As for tenting, while it's possible to set it up without the palm rest, we rather recommend it with the palm rest as it provides proper hand support.
With the above said, make your choice: