I use fedora 8(with alsa) and installed Realplayer 10 Gold RPM yesterday and met this problem too. ( I don't have SCIM in my system currently ).
I looked for the answer on the official pulseaudio and found this:
Real Player 10
Real Player 10 cannot be used with either Esound (note) or PulseAudio at this time. However, you can either use Real Player 8, or use MPlayer with the RealPlayer codecs.
The web page is here:
http://www.pulseaudio.org/wiki/PerfectSetup
scroll down and you'll find it.
Since the pulseaudio is a new feature on fedora 8 distros, only 8 has this problem. But I like 8 better than 7, it's much faster.