If u are in Linux platform and would like to play .rm file, then RealPlayer will be the right choice. Follow the below steps to install RealPlayer 10.
1. Go to the shell konsole
2. Login as a root user by using “su” command (or else use sudo command if you dont know root user password).
3. wget url
4. chmod a+x RealPlayer10GOLD.bin
Once the installation is done, when u execute the program, it will ask for License agreements and other stuffs for the first time. After successful execution u can use RealPlayer to play .rm, .ra, .rv, .rmvb files. Also it can be used to play .mp3, .3gpp files(mostly used in cellphone cameras) and the open source Audio format Ogg file.
RealPlayer 10 for Linux is FREE and if you like to view the official download site click here .