Abbreviations

K = Knit
P = Purl
k2tog = Knit two together
p2tog = Purl two together
SSK = Slip 1 knit-wise, Slip 1 purlwise, insert left-hand needle through both stitches from left to right and knit them together
Rib = K1, P1 rib

Method

Cast on an even number of stitches and put a marker between your last and first stitch

Foundation Row: Knit 1, *bring yarn forward as if to P, slip 1 purlwise, K1 - allowing yarn to make a sloppy diagonal loop over right-hand needle. Repeat from * to last stitch, yarn forward as if to P, slip 1 purlwise, yarn around needle (this is the same as the simple increase one does when purling).

Row 2: *Slip 1 purlwise, yarn around needle, p2tog (the purl stitch and sloppy diagonal loop); repeat from *

Row 3: Take yarn to the back as for K. k2tog (the knit stitch and the sloppy diagonal loop), *bring yarn forward as if to P, slip 1 purlwise, k2tog (the knit stitch and the sloppy diagonal loop) - allowing yarn to make a sloppy diagonal loop over right-hand needle. Repeat from * to last stitch. Yarn forward as if to P, slip 1 purlwise, yarn around needle.

Repeat the last two rows.