You can specify the thickness of the line up to 100 pixels. You can also select the color of the keyline from the Color Picker by double-clicking on the color square. You may also use the six preset options or save your own custom settings.
Examples of Keylines
Black 18: R: 0 G: 0 B: 0 Weight: 18px
R: 160 G: 23 B: 22 Weight: 50px