The Submitted Form ID cannot be automatically added to a field in a form by default. It would need to be manually updated in the form if you are using the Standard F1 Minimal Report.
If you would like to have the Submitted Form ID generating in a field of your form, then a Custom PDF Report will need to be created for it. This can be done with the assistance of the Formitize Production Team, who be able to further assist, simply email production@formitize.com.