diff --git a/contract_variable_quantity/README.rst b/contract_variable_quantity/README.rst
index e5786edf..7dccb894 100644
--- a/contract_variable_quantity/README.rst
+++ b/contract_variable_quantity/README.rst
@@ -25,6 +25,10 @@ Configuration
    * *contract*: Contract whose line belongs to.
    * *invoice*: Invoice (header) being created.
 
+.. figure:: images/formula_form.png
+   :alt: Formula form
+   :width: 600 px
+
 Usage
 =====
 
diff --git a/contract_variable_quantity/images/formula_form.png b/contract_variable_quantity/images/formula_form.png
new file mode 100644
index 00000000..23d03e5a
Binary files /dev/null and b/contract_variable_quantity/images/formula_form.png differ