I’ve made this once before.
It’s very simple but a lovely accessory for anyone.
The ridge line adds a little detail.
The rows and rows of consistent stitching enables speed.

Worked bulky and fingering together for warmth and drape.
CO 30.

Pattern instructs to work 8 r st st, then one row rev st st.
That’s a 9 row pattern obviously.
It causes one to have to purl rows 8, 9 and 1 of the next set.
Every other set ( end and beg) of 9 rows will have 3 p rows.

It’s faster and easier to work a pattern of 8 rows:
rows 1 - 6 alternating k, p,
then knit rows 7 and 8.
The next set of 8 rows begins with a knit row.
In this fashion, every set (end and beg) will have 3 k rows.

Tip
It’s a good idea to work the second stitch and second to last in st st to prevent the edges from curling in.
In other words:
beg of row, sl 1st pwise yif, k next stitch, then proceed with appropriate row.
end of row, work row as appropriate to last two stitches.
k2 every row.

Unfortunately, I didn’t do that, so I worked sc around instead. So much for my beautiful sl st edge. Now I have a beautiful sc edging.