You continue 'in pattern' over the 73 stitches. You have to just knit the knits and purl the purls as they face you to continue the ribbing on the back.
You started with k2, p1, k2 on 77 stitches, so for 73 stitches, you'd work p1, k1, p1, k2, p1 etc. You basically eliminate the stitches at the beginning and end of the rows.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry