When you create the RangeFinder device, the second (optional) argument is the offset pose of the Range Device:
// Create a laser range finder with and offset of 0 in X, 0 in Y, 0.3m in Z, , 0 in rotation
kt::RangeFinder scan1 = kt::RangeFinder("hello:laser:1",kt::Pose3(kt::Vector3(0,0,0.3),0));