VCDS-RKS can be installed on Windows 8 and functions as expected.
To do this, download the setup file (save it on your computer). In the file manager, right-click on the file and select "Handle compatibility issues".
It is recommended to use "Windows 7" as the installation environment. Then, go to "Troubleshooting Program Problems" and select "This program was working in previous versions of Windows..." and choose "Windows 7". TEST it and pay attention to the administrator symbol in the taskbar (Run Setup).
Later versions of the VCDS-RKS setup will start directly. 
Okay.
Best regards, Rainer.