They are legal here as well, I try to keep them available all year.
This year I'm trying a horse feed type salt. It's in 40kg bags. 95% salt
I selected a depression in the ground where it's unlikely to be washed away, and just poured in the whole bag. I put it out in August, and it was still there in considerable quantity when I was there this November.
In my area I think there may be enough natural salt sources that it doesn't get used as much as some areas. Still, it's something I can do to help keep deer/moose in the area.
I don't hunt specifically over the salt, as it would be a waste of time. It's not visited that often.