prawn：Prawn::Document#footer

#!/usr/bin/env ruby

require "prawn"

Prawn::Document.generate(File.basename($0, ".rb") + ".pdf") do
  footer [margin_box.left, margin_box.bottom + 25] do
    stroke_horizontal_rule
    text "And here's a sexy footer", :size => 16
  end

  start_new_page
end