In a large pot, bring the vegetable broth to a boil. Add the rice, vegan margarine, salt and red pepper flakes. Add the collard greens and bring to a slow simmer. Cover and allow to cook until rice is soft, about 20 minutes, stirring occasionally. Add a dash of black pepper and more salt and red pepper flakes to taste. For a spicier dish, mix in a 1/4 to 1/2 tsp cayenne pepper before serving. Makes four servings of collard greens and rice.