See, you're approaching this wrong. Your thought process should have been, "This question has been burning for a while, so I'd better read the first post of this thread and maybe use Search to see if it's been discussed before." Instead, you choose to post, and here we are.
This question has been burning for a while so I need to ask it.
I'm using 0/53/18 DW Frost and I totally understand saving Rime for KM procs on multiple targets. My question is on single targets, is it worth it to use Howling Blast when both Rime + KM proc or just stick with Obliterate?