Judging by the hole sizes, you should be screwing one in below the middle dimple on the left, and two below the middle dimple in the second vertical row. If those holes are too small for the included standoffs, then there are three larger holes - one between the middle and bottom dimples on the left, and and two holes on the right just above and below the bottom and top dimples, respectively.
When installed, the top of each standoff should be level with the top of each dimple.