With the standard Rails form_for, I was able to pass ajax requests though select and collection_select helpers as such:
<%= address.collection_select :country, @countries, :id, :name, {:include_blank => false}, "data-remote" => true, "data-url" => "/ajax/states", "data-type" => :json %>
I can’t seem to figure out how to do this with simple_form
Figured it out. You just need to add the this: