Sift together rice flour, cornstarch, icing sugar, and xanthan gum in a small bowl.

Resift the dry ingredients.

In a large bowl, beat egg whites with an electric mixer until foamy.

Add lemon juice, cream of tartar, and salt while beating.

Continue beating until egg whites are stiff.

Gradually add sugar while beating.

Continue to beat until the mixture is very stiff and glossy but not dry.

Sift dry ingredients, 1/4 at a time, over the beaten egg whites.

Gently fold in each addition until well blended.

Fold in almond extract.

Spoon batter into a prepared angel food cake pan.

Run a knife through the batter to remove large air bubbles.

Smooth the top with a moist rubber spatula.

Bake immediately in a preheated (350F) oven for 30-40 minutes, or until the cake springs back when lightly touched.

Invert the pan over a funnel or bottle until completely cooled.

Loosen the outside and inside edges of the pan with a spatula.

Remove the cake from the pan.