Wiktionary
ride herd on
vb. (context transitive idiomatic US English) To supervise a group of people, such as workers, and/or their actions, i.e. their work.
WordNet
Usage examples of "ride herd on".
Once that's done, I'll let the technical manager handle sound, and go ride herd on the actors.
I had to virtually ride herd on her constantly to keep her from proudly announcing her son's eminence.
For, Saturday or not, the federal district court down the hall is holding a special hearing, and they asked me to supply a deputy to ride herd on an Indian agent who ought to be ashamed of himself.