Once downloaded, this must be manually installed into the witcher 3 game folder. Im going to assume you already have reshade installed so i will skip that explanation. Once installed, open your game and press the home key on your keyboard. This will bring up the reshade menu. Once open, go to the home tab if not there by default and search through the list of shaders for UIDetectMulti, UIDetectMulti_before, and UIDetectMulti_after. Once located right click on UIDetectMulti_before and click send to top
 Do the same for UIDetectMulti after you've done so to UIDetectMulti_before. For UIDetectMulti_after, you want to send it to the bottom instead. Activate all 3 of them and the effect should now be turned on.