Built more than 60 years ago, the house is still in its original state and is a reluctant sale for the third-generation family owners.
Granddaughter Sue Holyoake said the bach held many fond memories.
"For us it's an end of an era. It won't be easy giving up what we've got there."
Bayleys agent Helen Webb said that when Sir Keith was asked on his deathbed in 1983 what his proudest achievement had been, he replied: "Kinloch."
Ms Webb said it was the vision of Sir Keith and his farming partners that saw plans for the Kinloch township evolve into the holiday destination it had become today.