Open RIM File
RIM extension files are mainly used for games developed by BioWare and are treated as resource image format. RIM files are basically a recursive image format for BioWare on its various game platforms.
RIM files are category game files. The most popular software that supports RIM files is ERF/RIM Editor.
RIM files are game data files used by some games developed by BioWare, including Neverwinter Nights and Star Wars: Knights of the Old Republic, similar to the ERF format also used by BioWare games and used as an application support file.
For more information, go to the official BioWare page