The style looks more 1970s to me. However the lack of a headsize ribbon inside the crown is a bit odd for the label, as those are usually very nicely finished hats. I am not sure how long the label existed, I do not recall seeing her hats in the 1980s, but it is a Canadian maker (if memory serves me today). By the 1980s you started finding more and more hats without the inside ribbon band as production values fell along with market demand. Sorry if I cannot help to date it more accurately.
As for the crease, it is really just "a crease". An inverted one. I wonder something. Have you tried pushing in the crease so the bash is more like a fedora crease? If it pops to that shape easily, perhaps that might be the original shape. If it resists or looks odd, then it is right as you have it.