Coat a 10-inch nonstick skillet with cooking spray; place over medium-high heat until hot.
Add zucchini, and cook 4 minutes or until crisp-tender, stirring occasionally. Stir in dill; remove mixture from skillet, and set aside. Wipe skillet with paper towels.
Coat skillet with cooking spray; place over medium-high heat until hot.
Combine egg substitute and next 3 ingredients, stirring well.
Add egg substitute mixture to skillet, and cook 2 minutes. Carefully lift edges of omelet using a spatula; allow uncooked portion to flow underneath cooked portion. Cook 2 additional minutes or until center is almost set.
Spoon cheese and zucchini mixture down center of omelet. Fold omelet in half. Reduce heat to low; cook 1 additional minute or until cheese melts and omelet is set.