Where the disc is lying shouldn't matter on an OB call as it's where the disc went OB. Honestly, though, I would mark first to be safe and to prevent arguments.
However, even if they are arguing a marking violation it requires a warning first.
However, even if they are arguing a marking violation it requires a warning first.
802.03 GA player shall receive a warning for the first violation of a marking rule. One penalty throw shall be assessed for each subsequent violation of any marking rule during the round.