When rendering with XPU, you have some additional options to configure. Depending on how your studio is set up, the way you configure your xpu settings may be different.

PrmanGlobalStatements has a renderVariant setting that you can set to choose to render with either RIS or XPU. There are also additional XPU settings to restrict it to use just the GPU or just the CPU. XPU - CPU can be especially useful for cases where you need to render on a machine that does not have a supported GPU.

If rendering with XPU or XPU-GPU, there is also a GPU Selection option where you can pick which GPU to use if your machine has multiple.

For interactive renders (Live/Preview renders), the settings in the Preferences menu will take precedence over the renderVariant selection, unless the "interactiveXPUSettingsOverride" preference is disabled. This is to enable individuals to customize their settings based on their machine rather than what is deemed a good default for show settings or batch renders.  You will still need to set the PrmanGlobalStatements renderVariant to one of the XPU options to enable XPU in the scene, but the enableGPU/enableCPU and gpuSelection preferences will be used instead of the PGS settings.

For batch renders, RfK provides a way to override the renderVariant and the GPU Selection as part of the katana batch command, i.e. katana --batch --katana-file=myfile.katana --render-node=Render -t 1 -- --prmanRenderVariant=xpugpu --prmanGpuSelection=0. Please note that the -- needs to precede the prman command line arguments.  The options for prmanRenderVariant are xpugpu, xpucpu, xpu, and prman. The prmanGpuSelection option accepts an integer value that represents the gpu number.