So far, we've completed the first round of petals. Next comes a set-up round for the second round of petals. The next line of instructions from the American Thread Company booklet is:
"3rd Row. * Ch 5, sc in back of work between the single crochets of next 2 petals, repeat from * all around."
The picture shows the back of the rose. I chained 5. (The chain sts are hidden by a petal in the picture. They really shouldn't be.) Then I placed the hook through the back of the stitch between petals -- the back of a dc from round 1 -- as the first step in making a sc.
The last stitch from the previous round is just to the left of the petal just to the left of the crochet hook (from our perspective) . (It's at about the 11 o'clock position.) When the round is complete, none of the sts from this round will be easily visible from the right side of the rose.