The car park for the falls is at the end of a short spur that is a bit rough and rocky (high clearance vehicle recommended though a passenger vehicle can make if you're careful). From the end of the road, you follow the creek upstream as the trail starts off pretty well-defined, but starts to become less defined the further you go. Eventually, some rock scrambling may be required and even when you get to the falls, you might have to scramble on the facing rocks (be careful as it can get very slippery here) in order to see the falls without the rock obstructions.

Look for the somewhat signed car park for the falls some 12km south of the township of Adelaide River on the sealed but narrow Dorat Road (Road 23). Give yourself about 20-30 minutes each way for the walk to the falls.

By the way, you might also see this waterfall referred to as "Robyn Falls." At least Lonely Planet spells the falls this way. However, my Explore Australia atlases spell it with the "i". Just so you know.