Preheat oven to 450°F. Put dry ingredients into a bowl and whisk briskly to mix. Add the shortening to the dry ingredients in small chunks. Using a pastry fork, cut shortening into the flour mix until it is a crumbly texture. Add rice milk. Mix together until dough forms a sticky ball. Knead dough on a floured surface. Continue to work dough, adding flour if necessary. Dough is ready when it no longer sticks to your hand. It will have a slightly silky feel. Roll dough into ball and place on ungreased pizza pan. Flatten dough and pat toward edges of pan. Brush with olive oil. Sprinkle with garlic powder. Gently roll the edges over to form a ridge. Bake for 12 minutes at 450°F. Top with your favorite toppings and bake for an additional 10 to 15 minutes.