You could always leave a comment for yourself at the expense of one extra comment character,
i.e.
especially if it's optional as if you forget to use call, you wouldn't know anyway.
and when you see an assignment such as
ColumnWidth = myHeight * 4
you know it's a function.
The signature of a function is different to a sub in that you should specify the type of the returned value. i.e.
myFunc(val1 As Int, val2 As Int) As Int
So that would be another clue when you come back to it.