My run is not meant to be rodent proof.
There are mice around but I keep traps set 24/7/365 in the shed that the coop is in.
Have only had 3 rats here, due to land clearing on an adjacent property, all trapped/killed.
Here's some good tips for aprons:
Good examples of anti-dig apron installation.
If rodents are prolific, burying the apron ~12" would be good.
https://www.backyardchickens.com/threads/wire-around-coop.1110498/#post-17093528
https://www.backyardchickens.com/threads/new-coop-project.1169916/page-2#post-18481208