social/social_media_xing/views/res_config.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
  <data>

    <record id="view_website_config_settings_ext"
            model="ir.ui.view">
      <field name="name">Website settings</field>
      <field name="model">website.config.settings</field>
      <field name="inherit_id" ref="website.view_website_config_settings"/>
      <field name="arch"
             type="xml">
        <xpath expr="//div[@name='social_googleplus']"
               position="after">

          <label for="social_xing"/>
          <div name="social_xing">
            <div class="oe_inline">
              <field name="social_xing"
                     placeholder="https://www.xing.com"/>
            </div>
          </div>

        </xpath>
      </field>
    </record>

  </data>
</openerp>