Hi,
For an RTMP stream, you can try JWPlayer by browsing the URL below:
http://www.jwplayer.com/wizard/
Provide your stream URL at the File field.
For example, you can test the player using the following stream URL:
rtmp://s2pchzxmtymn2k.cloudfront.net/cfx/st/mp4:sintel.mp4
Replace the File field with your stream URL to test your RTMP stream.
For an RTSP stream, you can use the VLC player, click Media > Open Network Stream, enter your stream URL, then click Play.
Cheers,
Don