Save FreeTextInvoice in PDF with job

I need to print a service sales invoice that uses the FreeTextInvoice class in PDF format.
My job is this, but instead of keeping it in the route that I indicate it shows it to me by screen


The route is my desk and in the debuger I see that he takes it and keeps it well.
What I need so that instead of being shown on the screen, the pdf is created on the route that I indicate.