Stir together the potato starch, almond flour, salt, and pepper. In a large bowl, add the onions and the potato starch mixture. Coat the onions thoroughly. Set aside.
Add the oil to a 12" skillet. It should be about ¾" deep. Heat over high heat.
In a medium bowl, add the white rice flour, 1 to 1 flour, baking powder, garlic powder, salt, pepper, and water. Whisk together until smooth.
When the oil is to temperature (365℉), add 6-7 onion rings to the batter. Shake off the excess into the bowl. Set each in a single file in the skillet. Cook until golden browned on one side before turning over with a tongs or fork, carefully.
When both sides are very golden, remove to a wire rack over a baking sheet lined with paper towels. Repeat for other batches. Keep warm on a wire rack set over a baking sheet in a 225℉ oven.