There are several places that could be leaking and showing up there. You haven't said what engine you have, and that really helps us as we try to answer questions, but some of the engines have an oil pressure fitting at the rear/top of the engine, right behind the intake manifold. If it leaks there the oil will go down the back of the engine and drip where yours is dripping.
Ditto the intake manifold as there's a "China wall" between the two banks on a V8 and the intake is supposed to seal to it. But sometimes it doesn't.
Then there are the valve covers, but on a V8 they don't usually leak down to where yours is leaking.
Last there's the rear main seal, which would easily put oil there. But to use the word "easily" in conjunction with a rear main seal leak is a dereliction of duty as replacing that is NOT easy.
So I'd clean things off using brake cleaner and try to figure out where it is coming from.
Gary, AKA "Gary fellow": Profile
Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker in front & 10.25 Spicer/Trutrac in back, & EEC-V MAF/SEFI