just FYI, text from propellerhead website:

If any samples have migrated from one system to another, make absolutely sure that the file format is correct afterwards. We have seen that samples that e.g. have been created on a PC, saved as aiff files and then moved over to a Mac, could appear as AIFC files on the Mac system. The AIFC format is a compressed AIFF file and cannot be recognized by Reason. If this happens You have to convert these files on the Mac, either by using a conversion utility or by simply changing the Creator-type, using e.g File Buddy. Stick to one file type, it doesn't matter at all to the end result if the files are .wav or .aif - when the ReFill has been successfully created it can be used on either a Mac or a Windows system.