Mix the rice flour, maida and rava with some water and make it into a smooth batter. Cover and keep it in a warm place for about seven hours to ferment. Heat a flat pan (Thava) and Grease it with a spoon of oil. Add some water in the dosa batter and make it into a thin batter. Pour 1/2 cup of the batter in center of the pan (tava) and quickly spread with outward spiral motion to form a thin pancake of about 8 inches in diameter. Dot the edges with little oil and cook until golden brown. Using a spatula carefully fold the dosa and remove from the pan. Repeat doing this with the remaining batter to make more dosas. Serve hot with chutneys or sambar. We can also make gothumai (wheat) dosas in the same way with out adding rava.