I would never trust those dll download websites, the only official (I hesitate to say trustworthy...) source is obviously Microsoft in this case.
Besides that, just copying it to the system32 directory doesn't work anymore for several reasons. First, since Windows Vista, Visual C++ runtime libs need to be in the appropriate WinSxS subdirectory and registered properly before windows tries to load any VC runtime lib. This allows proper version control and prevents overwriting with malicious versions.
Secondly, on x64, system32 is the wrong place anyway, despite MS keeping the name, system32 houses your 64bit dlls, while 32bit applications run inside an abstraction layer called "Windows on Windows64", short WoW64, and Rift is 32 bit. Hence 32bit dlls need to go into the SysWoW64 directory anyway.
For more you can visit: http://www.pcerror-fix.com/how-to-fix-msvcp120-dll-missing-error
