One way is to put it on ramps and measure from a fixed point near each wheel (same point each side for front and then another same point for the rear) to the ramp. If the front measurement is lower than the rear, you have rake. As to how much you have that's up to how you set up the suspension. This will also tell you if you're level offside to nearside, which is always a good plan.
For me the wheel arch gap is bigger at the front for the simple reason of clearance, hard cornering (hairpin) brings on a swam of bees noise from the tyre rubbing on the wing\bumper mounting point just above the outside edge of the front wheel. Just raised it a bit each lap session time out until it never happened. Could've maybe hardened the suspenison up perhaps but can drive the car to my ability at the moment so raising was the easiest route to getting rid with out having to adjust a millon things to compensate for harder suspension...or couldv'e hammered the offending mounting point into the middle of next week.
Not the only way to skin this cat though......