I almost never do very well with Karma as support. She might work better with melee champs in bottom lane, but even then she desperately needs gold to be effective. However, when I go mid/top she feels borderline OP at times, and that's why I get frustrated when I get the occasional "WTF KARMA IS SUPPORT NOOB" people. Most of my teammates are like "ok" when I go mid or whatever as Karma, but I still get the occasional people that just can't handle the concept of doing anything but support with her :/ stupid stigmas.
Karma CAN'T play meta support because she needs to last hit and she needs farm, she doesn't function without AP, meta support only works because of CC and general effectiveness without building any kind of offensive stats allowing you to just run auras, ward and let the carry get all the CS. Karma requires AP to function.
The only place Karma can play in the meta is mid, though she could function solo top against a lot of characters if people let her.