app/views/devise/invitations/new.html.erb
<h2><%= t "devise.invitations.new.header" %></h2>
<%= simple_form_for resource, :as => resource_name, :url => invitation_path(resource_name), :html => {:method => :post, class: "form-horizontal"} do |form| %>
<%= form.input :organisation_id, :as => :hidden, input_html: { :value => current_organisation.id } %>
<% resource.class.invite_key_fields.each do |field| -%>
<%= form.input field %>
<% end -%>
<div class="form-actions">
<%= form.button :submit, :value => t("devise.invitations.new.submit_button"), :class => "btn-info" %>
</div>
<% end %>