If you look through the original instructions for dances of the seventeenth and eighteenth century, you will meet the term “foot it” and probably wonder what it means. Indeed you may meet it in modern interpretations such as The Fallibroome Collection.
It's clearly not the same as a “set”, since there are dances such as “The Happy Pair”, “Red and All Red” and “A Trip to Castle Howard” where the original instructions contain both terms. I've asked around, and most people agree that it's an invitation for the dancer to use whatever step he or she chooses — to show his dexterity, express his feelings for the dance or impress his partner. For instance, in the Fallibroome dance “The Cuckoo's Nest” I might well use a rant step — and also for the four changes.
If the move occupies four bars rather than two, there are more choices available. See for instance the “Fancy step” advocated by Alan Winston in my “200 Years of American” section. In “Auretti's Dutch Skipper”, London Folk (a well-known display team for many years), I believe the men did something very similar to the fancy step:
Hop on left foot, tap right foot to side — hop left, right in front — hop left, right to side — hop left, right behind — then repeat reversing feet.
while the ladies did something less energetic.
The choice is yours — and of course you can always do an ordinary setting step if you wish.
And as always, there are other opinions! Thomas Wilson, in his “Analysis of Country Dancing”, (this quote is from the 2nd Edition 1822) says,
N.B. — It may be asked by those unacquainted with Country Dancing, what is meant by the term set? Foot and set are the same; it is merely dancing in your place to fill up the time in the music…