Decide on a "n" number. The smaller, the more ruffles, the more times you increase, the more stitches you have at the end to knit. I suggest starting with 3.
Cast on 20sts
row 1: Knit, knit 1 f&b into every nth stitch. (ie k2, k1f&b repeat to end)
row 2: Knit to end
row 3: Knit, knit 1 f&b into every nth stitch. (ie k2, k1f&b repeat to end)
repeat rows 2 and 3 untill you have a total of 10 increase rows
bind off