Your PACS server needs to know three parameters:
1) the ip address of the PC with RadiAnt installed
2) the port that RadiAnt uses for listening to incoming connections (11112 default)
3) the AE title of the RadiAnt (RADIANT default)
please have a look at this short video about PACS configuration:
https://www.youtube.com/watch?v=8eUsR13kon0
Hope this helps!