I writing in english - hope it is ok, my german is not that good (I understand most of it, but can\\\’t write that well)…
I do not now the Market Ready Germany so do not know if it is has the functionality or not. But it is wary hard to add a footer because by default there are no footer / header objects.
So if you want to add them you have to include them yourself in the code, and do the calculation of when it is to be shown (not easy).
But I you want to give it a try start by looking at this wiki page wiki/5_-_modules_and_development/orders/editing_an_invoice_pdf
Alternative you can have a look at our new extension Edit magento PDF extension