If he did get into the Roundup today, I would absolutely expect to see the vomiting that you're now seeing.
The lip licking and shaking can both be signs of nausea in dogs, and since the biggest thing we see in dogs who have ingested Round Up is digestive upset (vomiting and/or diarrhea), it sounds like he did get into it.
The good news is that this kind of digestive upset generally clears up within 24 hours...so what I'd do would be to pick up any food, and only allow him to have water in small amounts tonight. Nothing to eat though so that his stomach has a chance to relax and calm down.
Tomorrow morning, you can offer him some bland diet...boiled white rice and boiled hamburger in very small amounts for the day. If he keeps that down, then you can start to slowly reintroduce his normal diet until you're back to just his normal kibble.
If he's not feeling better by Tuesday, or if he develops any other unusual behaviors, then you should have him seen by a vet in your area. If you're not sure where one might be, you can go to: http://www.vetlocator.com and plug in your zip code. They'll point you in the direction of the one nearest to you.
I hope this helps.