Jun 13, 2016 - 12:44 PM
in reply to jrosten
The pages I linked to in my answer above will point you to the correct booking websites. Mind that such VIP seats are only available on a couple of trains between Zweisimmen and Montreux, so you'll have to search the regular timetable and/or the Golden Pass timetable carefully to find out which trains offer them. The timetable allows you to click the "plus" icon next to each connection and to study the many details that will be displayed. If any of them includes the remark "avec places VIP", those are the connections you should be looking for. Regular 1st class seats should be available for seat reservation in all Golden Pass trains. But as mentioned above, reservations for regular seats are not required.
Mind that you'll also need an additional 50% discounted ticket between Montreux and Saanen with your Regional-Pass Bernese Oberland. The rest of the trip is for free. Please refer to the validity map for details.