"Rab is an international goalkeeper who has played many games in high pressure situations in front of massive crowds," the Foxes boss told the clubs official website.
"Rab has taken a fairly substantial pay-cut to come to Leicester and that just shows his ambition.
"He has done it up in Scotland and he wants to prove himself down here.
"I am happy to have him on board.
"I think the fact that we have been able to sign him sends a message out to our supporters that we mean business this coming season."