It depends on the design of bow you intend to make. The narrower the limb design the more of an issue it will be.
Treat the nail as if it was a pin knot, i.e. a potential weakness, especially in tension. Compensate by leaving extra width at the spot, just as you should with a knot, or pin.
Also if you used edged tools or rasps a nail exposed on the belly side is going to wreck havoc. You have the option of carefully driving the nail right through, and out with a punch or punches,