the bg is kinda all over the place, it ruins the flow a little, you want your effects, bg and lighting to all flow together to help blend your subject in with your background and foreground so it feels more natural. The border is unneccesary, it seems a bit blurry. the render just needs to be blended in a little bit so it doesn't look sharp on the edges of your cuts. I like where you placed her it is ok composition for a vert sig.