Preheat oven to 350ºF. Line a baking sheet with heavy-duty aluminum foil.
In a large bowl, combine ground chuck, onion, garlic, tomato sauce, parsley, egg, salt, fennel seeds and rice. Mix with your fingers until well combined (but do not overmix).
Pat mixture into an 8-by-4-inch loaf and place on baking sheet. Bake until an instant-read thermometer inserted into center registers 160ºF and meat is no longer pink, about 1 hour and 15 minutes. Let stand 10 minutes on baking sheet before slicing.