Preheat the oven to 325ºF. (162°C)
Measure the rice flour, rolled oats, baking powder, cinnamon, and ginger into a mixing bowl and whisk till combined. Combine the peanut butter and water in glass measuring cup and stir with a fork till smooth and creamy. Make a well in the flour, and pour in the peanut butter mixture.
Mix on medium speed using a paddle attachment till just combined. Turn the dough out onto a slightly floured surface and form into a log, about 2 inches in diameter. Wrap in plastic wrap and chill for 1 hour.
When ready to bake, slice the biscuits 1 ⁄ 8 -inch thick and place on a parchment-lined cookie sheet. Bake 12– 15 minutes till they are dry and firm to the touch. Turn the oven off and leave the biscuits in another 20– 30 minutes.
Remove them from the oven, cool them on a baking rack, and store them in a cookie tin.