The resistance in your beer line needs to be calculated based on your individual setup and internal diameter of the hose. The easiest way to create resistance is by using the appropriate length of hose.

Generally the following hose lengths apply

for a 4mm ID beer line the length should be 1.8 to 2.5 metres

for a 5mm ID beer line the length should be about 3 - 4.5 meters

for a 6mm ID beer line the length would need to be over 5 metres

Using correct hose length is a better way of creating resistance rather than turning down the pressure in the regulator too much...which could cause the beer to loose carbonation over a period of time.