I don't have a real potato fork, but instead use a 5-tine pitchfork. Digging potatoes is a fairly straight forward process. Stick your fork in at the beginning of the row, push down until the handle is horizontal, then pry up the fork and hopefully it will bring potatoes up with it. Continue until you've dug up the entire row. Then go back and gather your taters into a pile so they are less apt to get lost in the loose dirt.
Potatoes don't grow too deep, depending on how high you hilled them. Mine are usually between two and six inches deep. So if I have nice dry, loose soil, digging rows is fairly quick work.
most of a row of yellow taters
As you can see, my yellow potatoes didn't do too well.
The reds, however, did much better. The picture below is the haul from about half of a row of red pontiacs.
When all my rows had been dug, all the buried treasure found, piled, cured, then put into the baskets I store them in, I ended up with two and a half bushels of potatoes. That is roughly one hundred twenty-five pounds of organically grown spuds.
That's gold around this little place here. All safely stowed in the treasure cave, er, I mean, the cellar. :0)
potatoes to last us all winter