I'm not 100% sure on the pricker. Forks would have been rare, as they were the "devil's tools", particularly as you get into the renaissance. Spoons are obvious, but the predominant etiquette with eating solid foods worked like this (admittedly in a hall, not so sure on campaign):
When entering the hall, you will wash your hands at a wash-basin on the way in. You carefully dry your hands on the towel that is there, careful not to get dirt on the towel itself.
Once everyone is seated, the food would be brought out and placed such that it's within reach of every set of four people. You would use the thumb and first two fingers of your left hand to stabilize the food, while using your right hand to cut that piece off with your knife (so you're only touching the part you're taking). Your left hand places it on your trencher (small plate). There, you use your left hand to hold things still using the same three fingers, and you use the three fingers of your right hand to actually eat.
This accomplishes a couple of things. First, the hand that goes back and forth between your plate and the common food never goes near your face (hygiene issue). While your right hand does get used to cut food from the common serving, it's holding the knife and not touching the food there (it only touches the pieces from your trencher). Secondly, only peasants eat with all five fingers, so it's more proper at your station to use only three fingers.
This action would be repeated as many times as necessary. The trencher is very small, so you're usually only taking and eating one thing at a time, such as a piece of meat, or a hunk of cheese. This is very different than what is done today, where you load up your plate all at once. Back then, that would have been seen as gluttonous.
Like I said, this is courtly manners, so I'm not sure how it translated to the field. I'd imagine that someone in the upper class would try to retain manners to some degree, but knights can span a wider gamut. So I'm not sure.
