Last time I painted something like that, a pint covered about 20 to 25 square feet. With only 16 square feet, one pint should do 2 coats. Don't forget to lightly sand the entire surface or use a primer. Use a damp rag to clean off any dust from sanding. Let the surface dry completely.

A quart of paint should be more than enough. You'll also want to get a quart of primer to go underneath.