I agree with everyone who aid the saddle needs to go back. 2" (three finger-widths if you have small hands like me) behind the back edge of the scapula is what the Society of Master Saddlers recommend, as SullysRider says.
If you do that I'd guess the front will drop too low, but if the width is correct that simply means a front flock adjust to bring the saddle back into balance. The only reason I can see for using a rear riser is if the cantle drops when mounted, which you can't tell from a static picture, unfortunately. And I could be wrong about the front, but the panel looks pretty flat to me and the horse as likely to have a bit of shape behind the shoulder.
Nice saddle! :)