How to print a ticket to a POS printer

Hi all ! I want to load and correctly print a document to a POS printer. The document has the correct size, etc. But when I look into the paper size, its the whole roll of paper which is wront obviously. If I try to fir the document it wont work, there is no way to set the page the same as the document size. 

Any ideas on how to do it?

Im attaching the PDF and the settings' screenshot so you can have the reference.

Thanks in advance !