Help on Photoshop

I am a picture framer. I need to put a frame around a picture on Photoshop.

The problem is that I have scaled the painting to 114cm x 84cm (it's actual size). I then have an image of a frame that needs to fit around said painting. However the frame is 9cm wide and it has to look in portion to the painting as if it was real life.
The frame must fit in the white boarder around the painting as shown in the image.
If this can be done I would need you to speak to me and show how you achieve this