Half Fisherman rib

Hi please can you help I am learning how to do half fisherman’s rib .I slip the first stitch and knit the first row ,that works out fine ,and then for the next row I slip the first stich and then I knit below the next stitch and then I purl the next one and continue like that until I reach the last stitch and that’s when I am left with a large

loop at the end and I don’t know why,I have undone my work so many times but I still end with a large loop please help.

Welcome to KH!
This video shows loose stitches along the right edge even though the first stitch is slipped knitwise. Is that the kind of loop you’re getting?

Are you slipping the first row 1 stitch knitwise? That’ll likely tighten up the loop.