Reveal original image means reveal the layer that the stroke is applied to. On transparent will give you only the stroke on that layer.
You have two options. Copy your paths to the layer with the signature and choose Reveal Original or select on transparent and use the layer with the path as a track matte for the signature.
In most cases it's best if you break the signature up into several pieces so hide the problems of overlapping lines. You'll see what I mean as you start revealing the signature.
You can also search the forum for this topic, we see it often.
My usual contribution: Carefully study someone slowly inking their signature. You will see the speed of pen movements are not linear and there are pauses for vector changes and pen lifts. Decide how realistic your animation needs to be.
Thanks, but it's stiill not working. I don't understand what is wrong. According to the tutorials, I import the signature, then trace the paths, copy them to a new composition with a solid, and then choose reveal original on the paint setting and it's supposed to reveal the signature below. Is this not how it works? When I copied the paths on the original, I couldn't do anything with them.
Nope. Reveal reveals the layer the masks paths are on not the layer or layers below.
You need to put your paths on the signature.
If you want to keep the paths on the solid then select On Transparent, place the layer just above the signature, and then set that layer to an alpha track matte.
Hope this makes sense.