Hi J calvin,
Believe it or not I went through this exact same question and reply on another forum about a month ago.
Len's response is accurate.
The amount of Whisker Biscuit that you see when looking through your scope is dependent on a couple of factors. It depends on the size of your scopes Objective lens. The larger your front (objective) lens is, the more of the biscuit will be visible.
If you are not using an HHA Optimizer and your scope is mounted directly to the Weaver Rail of the crossbow, you will also see more of the Whisker Biscuit.
Most TAC owners say they can see some amount of the top of the Whisker Biscuit when they are sighting their targets. I do not and have not ever had a view of any part of my rest, but that is probably because I'm using a 3 x 12 x 44MM compact scope with medium height rings and all the above is sitting on an HHA Optimizer.
Regards,
Jon