reporting-engine/report_qweb_pdf_watermark/views/ir_actions_report_xml.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
    <data>
        <record id="act_report_xml_view" model="ir.ui.view">
            <field name="model">ir.actions.report.xml</field>
            <field name="inherit_id" ref="base.act_report_xml_view" />
            <field name="arch" type="xml">
                <field name="attachment" position="after">
                    <field name="pdf_watermark" attrs="{'invisible': [('report_type', '!=', 'qweb-pdf')]}" />
                    <field name="pdf_watermark_expression" attrs="{'invisible': [('report_type', '!=', 'qweb-pdf')]}" groups="base.group_no_one" />
                </field>
            </field>
        </record>
    </data>
</openerp>