Preheat the oven to 170°C (338°F).
Soften the room temperature butter until smooth.
Add sugar to the butter and mix well.
Add the egg and mix until combined.
Sift in the rice flour and salt, then mix together.
Shape the dough into balls and place them on the baking pan.
Bake in the oven at 170°C (338°F) for 12~15 minutes.