What is the proper procedure for boarding at a station that has no ticket office or ticket machine if you have a reservation? Do you just show your reservation printout to the person collecting tickets?
It depends on the train. Assuming it isn't one of the very few trains currently enabled for eTicketing, it will fall under one of the two following scenarios:
Scenario A (Vermonter & Ethan Allen are good examples of this):
If booking more than 9 days in advance, you're tickets will be mailed to you through the USPS.
If booking less than 3 days in advance, you will need to talk to an agent and get a reservation # and boarding code and the conductor will accept payment on board and handwrite a ticket.
Between 9 and 3 days, you will be offered the option of a $15 express delivery charge - usually it makes sense just to wait.
Scenario B (Adirondack and most LD trains are good examples of this):
If booking more than 9 days in advance, you're tickets will be mailed to you through the USPS.
If booking less than 9 days in advance, but at least 6-12 hours before train departure time from it's originating station, the conductor will bring a printed ticket for you and give it to you on board (when booking you will be informed of this).
Close to or after train departure time, you will need to talk to an agent and get a reservation # and boarding code and the conductor will accept payment on board and handwrite a ticket.