Go up the Riffel 2 chairlift and then traverse in the backside to Hinter Rendl. In the centre of the bowl ski down 170 vertical meters and traverse right below a big rock. then go uphil to the Rendlscharte. From here you take the slope down right.
You end up on a wide and easy slope. at the bottom its getting a bit steeper. Traverese to the right here and follow the valley down to the village of Pettneu am Arlberg.