Spread margarine on one side of each slice of bread. In a medium bowl, combine broccoli, chicken, roasted red peppers, and cheese. Place bread, spread-side-down, in a sandwich maker. Spoon a heaping 1/2 cup of the mixture on the top of each bread slice. Place a slice of bread, spread-side-up, on top of filling, close sandwich maker, and cook until golden brown, about 2 to 3 minues.