Rear Spacer recommendation *Pic included*

[ohhh my]

Sorry for the bad picture/angle of the picture. It's the only picture I currently have on my computer that my nephew took.

I'm not sure if you can tell from the pictures or not, but the rear tires are tucked in and I would like to add some spacers to the rear to fill out the rear fender. How many mm spacer(if you can even tell) should I add? Also, is there a difference in brand? Will I have to get an alignment after adding spacers. How will spacers effect the handling?

Thanks