Yes, you are allowed to have both a roof box and bikes on the roof of your car when traveling with SAMSØLINJEN.
Is there anything I should be aware of?
The most important thing is that the total vehicle fits the ticket you have purchased.
Your ticket is always based on the length of the car, and this also applies when you have something on the roof. In most cases, a roof box or bikes on the roof do not affect the length, but if your vehicle overall takes up more space than expected, it may affect your booking.
If you are unsure, it is a good idea to check the length of your car including any equipment or choose a slightly larger ticket. You can change your ticket at the link here.
How does the boarding process work?
When you arrive at the port, you drive as usual to check-in. Here your car will be measured and placed so there is room for everyone on board.
The staff ensures that the cars are safely distributed on the car deck, even when there is equipment on the roof.