Hello.
I enabled Multi Variant Custom Field for this product named "Rozmiar".
It is shown on product details page.
But there is no info about this custom field on cart page.
How to enable that?
You don't mention the versions you use? See http://forum.virtuemart.net/index.php?topic=79799.0
But if it is VM3.2 then see http://forum.virtuemart.net/index.php?topic=136963.msg479108#msg479108 - this fix is already in VM3.2.1 which is still under test.
I use VM3.2