Not all fare booking codes allow seat selection on TAROM flights. The cheapest ones only allow seat assignment at check-in.
If you plan to buy a ticket from TAROM directly, you can assign seats when purchasing your ticket.
If you already have a ticket that includes a TAROM segment you can either:
- call TAROM and ask for seat assignment
- try to view your booking on KLM and assign seats (this does not always work)