Rick,
If one was to glue up the whole structure prior to glassing, you could use wood glue. But you have done it in stages and glassed the riser. At this point you will need to use thickened epoxy. To respond to your next post, thickened epoxy is used to add strength with the fibers in the epoxy and to fill any gaps. Unthickened might work on two surfaces that mate perfectly and is not under any stress, but your lip will likely have small gaps which even you might not see, therefore use thickened and be sure to rough up the surfaces good for a strong bond. Once you have the lip glued on, add some more cloth over the lip and onto the riser, for more strength.

When you say you are using heat, are you steam bending the pieces? If that is the case you will have to steam bend them one day and then epoxy glue them the next after the wood has dried. I use very thin strips and skip the steam bending stage, unless the customer wants a very hard wood that even thin is likely to split. Add an extra strip or two on the outside as the sacrificial strips that might split as you bend. Once made, you can plane and sand off the outer edge. With steaming, it helps to have and extra pair of hands helping as you will not have much time since the thin wood will cool quickly. With the epoxy stage, you will have ample time to get it bent around and clamped. Lots of clamps on the ready.

Good luck