acc_invoice_weight.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <record model="ir.ui.view" id="account_order_weight_form">
            <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="//notebook/page[@string='Invoice Lines']/group" position="replace">
                    <group>
                        <group class="oe_subtotal_footer">
                            <field name="in_weight_total"/>
                            <field name="in_net_weight_total"/>
                        </group>
                        <group class="oe_subtotal_footer oe_right">
                                <field name="amount_untaxed" widget="monetary" options="{'currency_field': 'currency_id'}"/>
                                <div>
                                    <label for="amount_tax"/>
                                    <button name="button_reset_taxes" states="draft,proforma2"
                                        string="(update)" class="oe_link oe_edit_only"
                                        type="object" help="Recompute taxes and total"/>
                                </div>
                                <field name="amount_tax" nolabel="1" widget="monetary" options="{'currency_field': 'currency_id'}"/>
                                <field name="amount_total" class="oe_subtotal_footer_separator" widget="monetary" options="{'currency_field': 'currency_id'}"/>
                                <field name="residual" groups="account.group_account_user" widget="monetary" options="{'currency_field': 'currency_id'}"/>
                                <field name="reconciled" invisible="1"/>
                        </group>
                    </group>
                </xpath> 
            </field> 
        </record>  



        <record model="ir.ui.view" id="account_supplier_order_weight_form">
            <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"> 
                <xpath expr="//form/sheet/notebook/page[@string='Other Info']" position="inside">
                    <group>
                        <group class="oe_subtotal_footer">
                            <field name="in_weight_total"/>
                            <field name="in_net_weight_total"/>
                        </group>
                    </group>
                </xpath> 
            </field> 
        </record> 


    </data>
</openerp>