I've been looking in to the same thing myself recently. The line from New Relic (or at least the line I've had in support tickets from them) is that support is very limited (particularly if you're caching your frontend).
That said, there are a few other options:
- Third party library that hooks in to New Relic specifically for Single Page Apps: https://github.com/uken/newrelic-timing
- Pingdom just launched RUM for SPAs too: https://www.pingdom.com/
There's also Caliper (http://caliper.io) but they are yet to launch with support for Angular
UPDATE: You Should also check out the latest New Relic docs regarding supported APIs in the Browser Agent: