The first thing to clarify is that Windows HCK Client 8.1 is not designed to install on "Windows 8 RT", a failure to install in this case is expected.  If you are in fact trying to install Windows HCK Client 8.1 on a system running Windows 8.1 RT, then
please make sure you follow all of the steps described in this section linked below, especially the part about installing the "Kits policy", this is a new requirement for Windows HCK client 8.1;

The first thing to clarify is that Windows HCK Client 8.1 is not designed to install on "Windows 8 RT", a failure to install in this case is expected.  If you are in fact trying to install Windows HCK Client 8.1 on a system running Windows 8.1 RT, then please make sure you follow all of the steps described in this section linked below, especially the part about installing the "Kits policy", this is a new requirement for Windows HCK client 8.1;

http://msdn.microsoft.com/en-us/windows/hardware/hh998740.aspx

From our troubleshooting section, we also mention that Windows HCK Client 8.1 is only designed to work with Windows 8.1;

From our troubleshooting section, we also mention that Windows HCK Client 8.1 is only designed to work with Windows 8.1;

http://msdn.microsoft.com/en-us/library/windows/hardware/dn393918.aspx

"8 RT. This is not a supported platform; however, you can install Windows HCK Client software on a computer that is running Windows RT 8.1."

"8 RT. This is not a supported platform; however, you can install Windows HCK Client software on a computer that is running Windows RT 8.1."