When in Amsterdam we intend on visiting an number of museums including the Anne Frank museum. From what I have read on various threads we have decided that we will purchase the Museum Pass especially since we will also be able to use it when in The Hague. I was on the Anne Frank museum website this morning to see about reserving a time for our visit, however it would appear that I will need to buy an entrance ticket on -line in order to do so. That kind of defeats the benefit of having the Anne Frank entrance fee included in the Museum Pass. Is there a way I can reserve an entrance time without having to buy an entrance ticket.

You don't need to buy tickets if you have a Museum pass, but you do need to book a time. You may well need to quote the number of your museum pass to get the timed entry, I haven't looked into that.
If you don't book a time you have to queue with everyone else regardless of museum pass.
Until recently they didn't even accept the museum pass. This is a compromise.

OK, just looked at the sit, and it only offers the Museumcard entry on the Dutch language site.
This is probably because the museum card is aimed more at Residents of the Netherlands than visitors.

However it is fairly easy for you to do from the Dutch site, I imagine the layout is the same as in English.

In fact I've just been though the English side and it does offer museum card as an option if you keep going through the booking process.

It's been a year now, but I'm pretty sure I was able to book a time without paying since I planned on having the card.

Also,

"The museum card is sold in selected museums and can be purchased also at Uitburo at Leidseplein:

Uitburo (AUB)
Leidseplein 26
Opening times: from Monday to Saturday: 10:00 / 18:00; Thursday: until 21:00; Sundays and Public Holidays: 12:00 / 18.00.
www.aub.nl"