Selvedge stitch? help!

I’m doing a project (with the imfamous raglan seams) in seed stitch - I’d like to plan ahead and put slevedge stitches at either end to help me with seaming later, but I’m confused - my seed stitch on both RS and WS is *k1, p1, repeat from *

I’ve read that selvedge stitches work best when they are knit on RS and purled on WS (like basic stockinette) - but do I need 2 extra stitches on each side to make this happen, or just one?

with just one, I imagine it would look like this, on RS, I knit 1, *k1, p1 to 1 stitch, K1,
on WS, I purl 1, *k1, p1 to 1 stitch, p1

would this get me what I need? or do I need to have K2, seed pattern, K2 on RS, and p2, seed pattern, p2 on WS

Thanks!
Becky

The selvedge edge will be used for seaming when you are done, so I would do it like a garter stitch, rather than a stockingette stitch, which has the nasty habit of curling. Even 1 extra stitch at the end of each row will work, just always knit it, or always purl it, to get the garter effect.

thanks for your help - i will give it a try