Make sure your camera is all set up and running. Maybe have a look first at the camera quick-guide guide to get started.

Once you're all set up, log in to the WebGUI of the camera by browsing to its IP address. Navigate to Video and have a look at the Video Encoder settings as seen below:

The part to copy is the 'stream name' which is by default 'live/av0' ('live/av1' is for the second/sub stream with much lower resolution)

Next, open Potplayer and press CTRL+U, or navigate through the Menu > Open > Open URL...  

And enter the RTSP address for the stream, and hit 'OK'. 

In our default case it would be RTSP://192.168.5.163/live/av0 (or including the default RTSP port number :  RTSP://192.168.5.163:554/live/av0 )