Hmm, well, to be honest, I don't use RARs f'er this exact reason. They don't work with FH and they are a big pain to work with, since ye need to download a whole new program just to extract files and read them. I'll try m'best to work with the limited knowledge I 'ave on them and I hope that 'twill help ye.
First, if ye don't 'ave a RAR program, 'tis best to get one now. WinRAR seems to be the favorite amongst the users of this sort of file. Next, right click the RAR file and an option to extract the files should be there. Go through the process of extracting and see what is inside of this compressed file. The material cgf file should be in there, in some form or another. If 'tis a txt file, ye can edit it with Notepad, or a similar text editor, and save it as a cgf.
If this didn't help ye, I can try to find someone more knowledgeable in this area of expertise. G'luck with that preset!
