Hi Serge,
Not sure if you have looked at any of LOGic's QSL reports but that is the best place to start. Navigate to Reports, QSLing and click on QSL Cards, that will pop-up a window with many pre-existing QSL Card reports, some will print multiple QSO's on a card, some a single QSO per card, some print multiple cards per sheet, others a single card. Try to find one that is close to your design layout and it can be copied and modified to what you need. Also, take a look in LOGics help and the topic "Report Writer" and "Customizing Your Own Reports", both are good sources of info. Also, check out YouTube video
https://youtu.be/_8CBFNuL8x0 ,it describes how to change the size of a card within a QSL Card report.
I have old style QSL cards with pre-printed fields on the back of the card and easily modified one of LOGic's pre-existing QSL Card reports to match the data field locations on the card. It works very well.
Let us know and we can try to help with modifying an existing report to get what you need.
73 de Brad, N8GLS