Flash Player does not support RTSP. Are you sure you require RTSP and not RTMP or Flash/HTTP streaming?
Take a look at this tutorial on
How to set up video on demand streaming which explains the configuration and playback options using Flash/RTMP, Flash/RTSP, Apple HLS, Silverlight and RTSP playback. I think you will find the playback examples particularly helpful. You can apply the same approach to audio files that are described for video in this tutorial.