Frost Strike with Killing Machine.
Obliterate with two runes/When KM procs and you have no RP (this will change with the change to runes).
Frost Strike to avoid RP capping.
Howlilng Blast with a proc, Frost rune, or Death rune.
That said, memorising this is pointless as we haven't seen the changes to the DK rotation that will be introduced by the next expansion yet.