This term relating to a legal agreement can be confusing and does not relate to financial penalties. Feet refers to the lower part of a sheet of parchment. Fine is an alternative name for a ‘final concord’, the formal name for this type of document.
Three copies of a legal agreement would be written on a single sheet of parchment, one at left, one at right and one across the foot of the sheet. The parchment would then be divided into three pieces: one was given to each party to the agreement and the piece at the foot was retained by the court.
This practice was introduced in the 12th century and continued until the 19th century. It was sometimes used for conveyance of property.