Drop rate on familiars

I guess this can bring up another question, most people that I know are unsure if this is true or not, not even sure if this is answered anywhere to begin with but.

What matters when it comes to drop rate (mainly at bosses)?

1. The person who does most damage will have his/her drop rate counted when the target dies, even if people with 1x drop continue to attack?
2. The person who does the final hit?

I understand if this cannot be answered, but thanks anyway.

It's the person that does the final hit. You can usually test this at normal monsters.