While the native effect of the compatability kit is to provide DX7 support and extend handling of certain aspects of the game, it alone will not enable RTX in Dark Messiah. THere are additional things that must be installed and particular hardware.
Ray Tracing is a heavy load on GPUs and you need to make sure you have hardware that will work with it. While the DLSS features of Nvidia cards may naturally mitigate the performance cost of using it for this mod, some older cards may struggle.
The binaries used in Portal RTX were specifically tailored to work with the source engine, so you will need to download this. While we do supply the time-of-testing binaries of Portal RTX at your convenience, of which more information is given in the Portal RTX section of this wiki, using the latest binaries is always advised. You can grab the basics here: https://store.steampowered.com/app/2012840/Portal_with_RTX/
The real power of RTX Remix comes from these two open-sourced libraries made by Nvidia. We will be only using specific components of each however, and while the later sections will show you exactly what to do, it's important to know where they come from.
A collection of both repositories are available at the RTX Remix repository here: https://github.com/NVIDIAGameWorks/rtx-remix
For individual repositories:
NVIDIA Bridge: https://github.com/NVIDIAGameWorks/bridge-remix