Peja (Peć (Пећ), or Peja/Pejë in Albanian) is a city in the west of Kosovo.
About 10 minutes walk from the city center there is a roundabout along R107, right next to the Karragac park. Rught after the roundabout you can find a bus stop, where it's easy for cars to stop. After about 10 minutes we first got a ride to Gjakova, then another all the way to Prizren.
North towards Rozaje, Montenegro
Walk on the M9 towards east and ask drivers on the parking to get a ride to the roundabout where the road to Rozaje separates from R101. Then hitchhike from there on the road to Rozaje. It is almost impossible to catch someone in the city who is directly going to Rozaje, so it is recommended to take a little ride to the point especially because it is quite easy to get these little lifts in Kosovo.
Other useful info
It's fairly easy to hitchike along the M9 road, surrounded by the picturesque Peja Canyon and the white river. Four of us got all the way to Kuqistë pretty much instaniously from Peja, and we split up on the way back and had no trouble getting a lift back either. From Kuqistë one can hike for one hour and get to lake Liqeni, and there is even two restaurants on the way!