rma/crm_rma_claim_make_claim/views/claim_line.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
    <data>
        <record model="ir.ui.view" id="crm_claim_line_form_view">
            <field name="name">CRM - Claim product return line Form</field>
            <field name="model">claim.line</field>
            <field name="inherit_id" ref="crm_claim_rma.crm_claim_line_form_view"/>
            <field name="arch" type="xml">
                <xpath expr="//header/button[@name='set_warranty']" position="after">
                    <button name="button_rma_vendor_render_view"
                        string="Create Supplier RMA"
                        type="object"/>
                </xpath>
            </field>
        </record>
    </data>
</openerp>