Knit the given number of stitches. Work the next 2 stitches as a ssk (slip-slip-knit), but drop only the first stitch on your left hand needle off the needle.
The second stitch that was part of the ssk is still on your left hand needle and is now the first stitch on your left hand needle.
Knit the first and the second stitch on your left hand needle together and drop the stitches off the needle.
You have now worked a centered eyelet.
Repeat Step 1 – 3 as many times as needed.