This is from the program's splash screen when you run it:
1. Go ahead download and launch the application from the link below. Inside its main menu, press on the "Enable Test Mode" button and follow the instructions on the screen. This will enable TESTSIGNING mode, which allows unverified system files to be loaded.
2. Now all you have to do is to add the unverified signature to the required system files. To do so press on the "Sign a System File" button from the main menu, and enter specific filename including full path. For example: if ATITool64.sys from C:\Windows\System32\drivers refuses to load due to driver signature enforcement, you should type: "C:\Windows\System32\drivers\ATITool64.sys", and if you would like to sign more than a single file, just repeat this procedure until you’re done, and finally reboot.
After you enabled Test Mode and added signatures to the required system files, they should bypass Windows’s driver signature enforcement and load without any issues. However, if for some reason you are interested to revert it, you can re-launch the application, choose "Disable Test Mode" from the main menu, and reboot. If you encounter issues or having questions, feel free to post it on our forums.
Just follow the directions in the last paragraph.