Index: rolereference.module
===================================================================
--- rolereference.module	(revision 52)
+++ rolereference.module	(working copy)
@@ -636,6 +636,9 @@
   $references = _rolereference_potential_references($field);
 
   $options = array();
+  if (!$field['required']) {
+    $options[''] = t('Please select');
+  }
   foreach ($references as $key => $value) {
     // Views theming runs check_plain (htmlentities) on the values.
     // We reverse that with html_entity_decode.