For seed st (seed), K in P sts and P in K sts.
Beginning with K row, for st st, alternate K and P rows.
Cast on even number (70 will make it about 28")
Row 1: (K1, P1) across.
Row 2-4: Work in seed st.
Rows 5-within last 4 rows of completion: Seed 4, st st across to last 4 sts, seed 4.
4th row from end: Seed 4, (K1,P1) across to last 4 sts, Seed 4.
Last 3 rows: Work in seed st.
Bind off.
You may want to make the seed stitching around the edge wider than what the pattern calls for. This is what helps it to lay flat.