Is it leaking from behind the front crank pulley, if it is then its the front crankshaft oil seal, never done one of these before, you really need the Haynes on this but the seas are only circa £15 and you would have to take the front crank pulley off to do it so it may be an engine out job.
I would try and get the vehicle on a ramp and have a look around the sump area, just in case the seal has gone here and is possibly misdiagnosing a crank seal.
My advice if you cant ramp it is to get it on axle stands, get a good inspection lamp and have a real good look around the pulley area, it should be self explanatory, the Haynes will steer you in the right direction..