account_invoice_view.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
  <data noupdate="0">
    <record id="invoice_supplier_form" model="ir.ui.view">
      <field name="name">account.invoice.supplier.form</field>
      <field name="model">account.invoice</field>
      <field name="inherit_id" ref="account.invoice_supplier_form"/>
      <field name="arch" type="xml">
        <field name="supplier_invoice_number" position="attributes">
          <attribute name="required">1</attribute>
        </field>
        <!-- remove the name to move it in a better place -->
        <xpath expr="/form/sheet/notebook/page[@string='Other Info']//field[@name='name']"
          position="replace">
        </xpath>
        <field name="reference_type" position="after">
          <label string="Enter the reference in the Supplier Invoice Number field"
            class="oe_inline"
            attrs="{'invisible': [('reference_type', '!=', 'none')]}"/>
        </field>
        <field name="reference" position="attributes">
          <attribute name="attrs">{'invisible': [('reference_type', '=', 'none')]}</attribute>
        </field>

        <xpath expr="//field[@name='reference_type']/parent::div" position="after">
          <field name="name"/>
        </xpath>
      </field>
    </record>


    <record id="invoice_form" model="ir.ui.view">
      <field name="name">account.invoice.form</field>
      <field name="model">account.invoice</field>
      <field name="inherit_id" ref="account.invoice_form"/>
      <field name="arch" type="xml">
        <xpath expr="//page[@string='Other Info']//field[@name='name']" position="replace">
          <field name="reference" string="Customer Reference"/>
        </xpath>

        <field name="fiscal_position" position="after">
          <field name="name"/>
        </field>

      </field>
    </record>

  </data>
</openerp>