According to Apple gospel, function keys are partly going the way of the dodo
so F3/F4 can, like in the good old days, be hard to reach for some users.
@table @kbd
@item @key{F3}
+@itemx C-x (
Start defining a keyboard macro
(@code{kmacro-start-macro-or-insert-counter}).
@item @key{F4}
+@itemx C-x e
If a keyboard macro is being defined, end the definition; otherwise,
execute the most recent keyboard macro
(@code{kmacro-end-or-call-macro}).
@item C-u @key{F3}
+@itemx C-u C-x (
Re-execute last keyboard macro, then append keys to its definition.
@item C-u C-u @key{F3}
+@itemx C-u C-u C-x (
Append keys to the last keyboard macro without re-executing it.
@item C-x C-k r
Run the last keyboard macro on each line that begins in the region