Line the baguette pans with baking paper, folding the ends to enclose and prevent spillage.
Using a stand mixer, blend the rice flour, tapioca flour, sugar, yeast, xanthan gum and salt on low speed to combine
Add the water, olive oil, egg whites and vinegar to the dry ingredients.
With the mixer on high (Kenwood speed 4-5), beat the mixture for 3 minutes. (The mixture will resemble whipped cream in appearance.)
Using a wetted spoon, spoon the dough/batter into the lined French baguette pans. Smooth the top with a wet spatula.
Drizzle over a little olive and, using a flexible spatula, carefully coat the top of the baguette with the oil.
Set the baguettes to rise in a warm place until doubled in size.
Bake for 45 minutes in preheated oven.
Remove the baguettes from the trays and place directly onto the oven rack and continue to bake for an additional 7 minutes.
Remove from the oven and allow to cool completely on a wire rack.