One way to do it is to add a layer. Go back to the first layer and select the cloud, then paste it to the second layer and place it where you think the reflection should be. You may have to do a little erasing of the sky that got copied with the cloud, depending on the final transparancy. Flip it upside down, and maybe stretch it a little longitude wise. Then increase the transparancy of the layer until you like it.
I like it. It looks pretty realistic to me as is. Sometimes, depending on the sun, angles, and the waves, if any, you don't get much reflection.
If God intended aircraft engines to have horizontally opposed engines, Pratt and Whitney would have made them that way.