In my earlier response, you need a shank that is made for your Bernina 807 and Berninas made in that era. Only "Old Style" Bernina presser feet and adapters will fit your machine. No other brand will work, not Singer, not Janome, not Brother, nothing but Bernina Old Style. There are several Bernina old style presser feet. Look for presser feet with the number printed in black ink or presser feet that have the number stamped into the metal. Do not buy a Bernina presser foot with red numbers--will fit only newer Bernina machines.
If you want to use the Singer buttonholer attachment, it needs to be for a straight shank machine. You will need to have a Bernina shank adapter for your machine. Bernina Presser Feet
(down at the bottom of the page, click on the blue text that says "Bernina Shank Adapter" On the next page, scroll down to the last two items that indicate they are "Old Style." The first Old Style item is the shank adapter you would need to attach the Singer buttonholer attachment to your machine. (Am assuming it will work, no guarantees!) If it doesn't work, then you will probably not be able to use the Singer buttonholer with your Bernina machine.
This shank adapter would fit your machine:
If you are looking for a snap-on adapter, it needs to state that it will work with a Bernina Old Style machine, ie the old Record machines (930 Record, 830 Record, 730 Record, 707, 807 Mini, 630 Record, and 530 Record--or in other words, Berninas manufactured prior to probably 1996). Bernina Presser Feet
(down at the bottom of the page, click on the blue text that says "Bernina Shank Adapter" On the next page, scroll down to the last two items that indicate they are "Old Style." If you are looking for the snap-on, go to the very last item on the page (Old Style). This will fit your machine. Remember, if it says Old Style, it should work on your machine.
This snap-on shank will fit your machine: Presser Foot SNAP ON SHANK Adapter Bernina Old Style 530 532 1630...
This presser foot will fit your machine: http://www.ebay.com/itm/BERNINA-ORIGINAL-20-SATIN-DECORATIVE-STITCH-FOOT-OLD-STYLE-830-1530-930-etc-/132055492681
This is an entire kit of snap-on feet with shank (included) that will work on your machine: http://www.ebay.com/itm/20-Feet-Set-for-Bernina-Sewing-Machine-Old-Style-530-1630-Models-/381790565625
Here is a kit of snap-on feet with shank (included) as well as the buttonhole attachment you were asking about: 17 Feet Set for Bernina Sewing Machine Old Style eBay
Although, I believe you will be able to make only straight buttonholes with this buttonhole attachment.
Hope this helps.