A picture of the panel would be helpful. When I searched I was only able to find one panel and the picture was very small and hard to see.
I guess it depends on how much work you want to put into it. I think charity quilts are worth making beautiful, so I would probably add a couple of borders of a complimentary fabric, then applique flowers that look like those in the print on one of the borders. If that's too much, you could always surround it with a border of simple pieced blocks, or flying geese maybe.