This article is from the comp.sys.acorn FAQ, by Paul Vigay with numerous contributions by others.
Currently, sort of. A Real Audio player exists for NCOS but this is not useful for most RISC OS machines due to it's dependance on the presence of hardware Floating Point. An integer arithmetic version has been made by Warm Silence Software for StrongARM equipped machines but it currently cannot be released due to licensing issues.
However, Kira Brown and Justin Fletcher ported an Amiga RA player to RISC OS and you can download the latest version from her web site at http://www.neutralino.demon.co.uk/
This version however will not play 'streaming' RealAudio, and many of the newer RA files.