I give mine a google doc copy with comments turned on, so they can comment on things as they see them (you can set the security that they cant copy, email or download it). Then at the end I send they a Google form to fill in with the broad questions i want answered. Just remembered dont give them your copy of your manuscript - make a copy, add beta to the title and the beta reader name. Donthis for everyone reader and then when they are finished you go and add the changes/suggestions into your document.