I had an issue with loading RF 7.5 in windows 10, the issue came up because I installed Windows 10 as soon as it came out (Before the windows update for direct x 9.)
It's just a slight pc pain, not a bad problem. If yo get a message when trying to start RF 7.5 that a Dll file is missing or corrupt with a code 126, you need to install Direct x 9C.
Direct X is backward compliant, so it is OK to run older files in DX 11, but the DXstub won't work in windows 10, DX 9C is a Windows 98 32 bit executable,
To load windows DirectX 9.oC, you need to download the redistribute-able package, extract the files to a new folder, and right click the setup.exe file, and choose (run as administrator) from the menu. When the security screen pops up, answer yes to continue, and if the install package kicks out an error message, just run it again, then restart windows and RF 7.5 will run perfectly.