Sounds like knitting into the front and back of the stitch. Like this?
That’ll work just fine. You only want to increase from one stitch to two sts each time.
The pattern directions are, " rib 4, *inc in each of next 2 sts, rib 3, rept from * to last 5 sts, inc in each of next 1 sts, rib to end."
So, work 4sts in rib, (inc in one stitch, inc in one stitch, rib3) then after 17repeats of the directions in parentheses, inc in the next stitch and rib the last 4sts.
It may help to mark off every 5sts of the repeat with stitch markers to make sure that you stay on track. Each repeat of 5sts will be 7sts after you complete it.