Public transportation: The most sustainable travel option is by train (coming from Villach) to Hermagor. From Hermagor, you can then take the bus to Rattendorf.
Alternatively, there is also the option of taking the bus from Kötschach-Mauthen or Villach to Hermagor or Rattendorf.
From Tröpolach, you can either take the Almshuttle (depending on the season and availability - advance booking by phone at the Mobilbüro is necessary) or walk - from here it is approx. 3 hours (uphill) to the actual start of the tour.
Details at - Mobility information Nassfeld and route planner Kärntner Linien
Arrival by car:
Take the B111 (Gailtal Straße) to Jenig - in the center of the village turn off to Rattendorf. Drive through the village - follow the signs for "Rattendorfer Alm" to the south (the road becomes a gravel road). There is a crossroads just outside the village - turn right here and follow the long gravel road to the parking lot just below the Rattendorfer Alm.