:(Sorry to hear about your loss, it's so sad when we lose our animals. We used an electric poultry net fence, added a second for a while to give even more space and never had a fox problem either back in England or over here where there are lots of hungry foxes! As someone already said, you need to test it regularly ...not nice but needs must, to ensure it's working. We now have a couple of peacocks roaming free and I've seen them chase a fox off the drive so, if you have room, and nice neighbours get a peacock! If you have lots of land...get a couple of alpacas as they too see off foxes and can be used to guard poultry!!
Another suggestion is to keep changing things around in the garden, don't let the fox feel it's familiar territory. Put out a scarecrow, move it about, leave things in different places and move them often...then do the peeing stuff, the hair etc...belt and braces!
Good luck...you can never be 100% but you can always do a little more to keep your girls safe.
Judi