Everyone was at least once ported into an empty instance while waiting for a RF to pop and it is annoying to wait for another one. So, before Funcom fix this problem, let me show you a quick way how to get ported to the full instance with all the players!
1. When you get ported into empty instance, DO NOT close the popup window - just move it to the side so you can see.
2. Turn back and go to the EXIT doors of the raid instance (here it is in BRC).
3. Click on the doors and select LEAVE THE RAID while the popup window is still on your screen (this wont give you the Deserter debuff for 30min).
4. Once ported back from where you started, move back that little popup window and finaly click OK button. You should be ported in the right - full instance without waiting for another RF to pop.
Disclaimer: this workaround may not work for everyone (there are more bugs to RF like the famous inability to leave) but for me it works 100% so far