When I used it in the coop, I pushed them all into the 12' side of the coop at roost time and closed off the 8' side so they were all in the same room. I sat the vaporizer on a plastic lawn table and pointed the spout toward the roost, but it was about 8 ft away, closed down the windows a bit and a fan was on low, blowing the mist toward the roost. I let it go for about 45 minutes or so, to make sure that they had all breathed in the mist, though not all were having issues at the time.
The ones that had the real trouble were brought into the house and put in a wire dog kennel. I put a sheet around two sides to sort of "hold in" the mist, sat the vaporizer on the floor a couple feet away from the cage and let it mist for about 10 minutes at a time, several times each day.