Custom rule for Karabiner(KeyRemap4MacBook) to change input source using right option key

private.xml

<?xml version="1.0"?>
<root>
  <item>
    <name>Change Input Source when press right option key.</name>
    <appendix>Option_R to Command+Space</appendix>
    <identifier>private.change_input_source_with_right_option</identifier>
    <autogen>--KeyToKey-- KeyCode::OPTION_R, KeyCode::SPACE, ModifierFlag::OPTION_L | ModifierFlag::COMMAND_L</autogen>
  </item>
</root>