What you see (and hear) is what you get, when animating lip sync in stop motion. If it looks right for the sounds when you play it back, then it works- regardless of what specific mouth shapes you've used. You can determine mouth shapes right in Dragonframe as you animate, or you can refer to Figure 13.9 in the book to see how you can break it down in advance, using a dialogue sheet. Check out this clip for some practice.