Fubenvet + Free Ranging?

Into my second day with the flubenvet and did I read it right, after doing a search, that your chickens are not allowed to free range or roam in the garden??

Hi
I have just finished worming my hens and kept them in for the seven days as advised, although mine do have a stable to roam in.
I had previously wormed them and didn't keep them in and 5 weeks later worms were present in one. 
They definitely ate more pellets the week they were not allowed to free range subsequently getting more flubenvet.
I worried about them not getting their corn in the evening but they really didn't miss it that much. I think we enjoy giving them their treats almost more than they enjoy getting them. 
The only other way to dose them is if you can give them an individual dose of flubenvet each on a treat eg, grape, although i am not sure how much etc. and you would have to make sure that each hen gets her medicine.