[setishock]

ACP > Styles & Templates > Style Manager > Drop down the menu on the AP theme and select > Edit Templates > Postbit Templates > postbit.

Just past midway you'll be looking for a section that looks like this:

<!-- sig -->
			<div align="center">
<img src=http://animeappeal.com/forums/picture.php?albumid=118&pictureid=4142>
<br />
				$post[signature]
			</div>
		<!-- / sig -->

That's mine out of another theme but what you're looking for is in the same place.