How to use Webform to accept values from a referenced field value

Hi all,
I have 2 content types: Tour and Agent.
Agent has email field which referred to Tour using References module. (There's no email field in Tour content type).

How can i embed Webform as a booking/reservation form for any Tour node which when sent, email to the referred Agent (provider) instead it to me as the Admin. FYI, this is not a multiuser development.

Entityform seems not working for me - it crashed every time i enabled Rules and Entity modules.

Needed help.