And what you want to have on the "button"? I used it in toolStripMenu. If I set size, no change. But when I set size and image on the button, it has size, which I want and shows full image.
CheckBox bold = new CheckBox();
bold.Appearance = Appearance.Button;
bold.Size = new Size(16,16);
bold.Image = Properties.Resources.b;
Where image from Resources has size 16x16px.