Melt margarine in large nonstick skillet over medium-high heat. Add onion; cook and stir until tender. Add rice; stir to coat. Add broth; bring to a boil. Reduce heat to low; cover and cook 10 minutes.
Stir in vegetables, ham and marjoram. Bring to a boil. Cover; simmer 8 to 10 minutes or until liquid is absorbed and rice is tender, stirring occasionally. Stir in cheese until melted.