If an answer has no references, should I use the "Very Low Quality" flag, or "in need of moderator attention" flag?
In addition to JamieC's answer:
Don't hesitate to also add your own comment. Here is the template I use:
[Welcome to Skeptics!](https://skeptics.meta.stackexchange.com/questions/1505/welcome-to-new-users) Please [provide some references](https://skeptics.meta.stackexchange.com/q/5) to support your claims.
There are some more suggested templates and actions here: Guidelines for Inadequately Referenced Answers