I purchased this laminated ad at a Record Convention some time ago.
This looks like it was from a '72 Rolling Stone Magazine since Killer
came out in November 1972.
The size of the page is 10.75x14.5 inches laminated on another piece of stock.
You can see the ad on the other side which is a Christmas album ad.
I had to tile the scan so that's why the horizontal line going across the middle of the page.