Excellent to hear you are a sauna bather and are looking to enhance the experience.
To date, equipment does not exist to automatically add aroma into the sauna room.
Simply purchase your favorate aroma at SteamSaunaBath and manually mist it into the atmosphere. Do not put oil on the sauna rocks or wood.
Check out AromaMist oils at http://www.steamsaunabath.com/catalog/essential-oils-4oz-bottle-aromamist-p-441.html?cPath=64_75
Keep the heat on!