app/views/spree/checkout/payment/_paymillcreditcard.html.erb
<%= render :partial => "spree/checkout/payment/paymill/form", :locals => { :payment_method => payment_method } %>
<script type="text/javascript">
var PAYMILL_PUBLIC_KEY = '<%= payment_method.preferred_public_key %>';
</script>
<script type="text/javascript" src="https://bridge.paymill.de/"></script>
<%= render :partial => "spree/checkout/payment/paymill/token_handling" %>