module FFaker::IdentificationESCL

def dv(rut) 

def dv(rut)
  total = rut.to_s.rjust(8, '0').split(//).zip(%w[3 2 7 6 5 4 3 2]).sum do |a, b|
    a.to_i * b.to_i
  end
  (11 - total % 11).to_s.gsub(/10/, 'k').gsub(/11/, '0')
end

def rut

replaced by a 'K' character
The last Y is a modulo 11 validation code. In the case the result is 10, it will be

http://es.wikipedia.org/wiki/Rol_%C3%9Anico_Tributario
RUT is the Chilean ID, followed by format: XX.XXX.XXX - Y 
def rut
  # Rut is gonna be between 1.000.000 and 24.999.999
  n = rand(1_000_000...25_000_000)
  "#{n}-#{dv(n)}"
end