configure DSCP traffic shaping

Hi All

I'm trying to prioritise WebRTC traffic on my FG 200b, 5.2. 

I enabled DSCP using: 

config system global    set traffic-priority dscp

and set 46 value to high:

edit 46       # EF         set ds 46         set priority high

Would this be enough for the firewall to prioritise 46 traffic? or do I need to configure anything else?

I was following this post: https://forum.fortinet.com/tm.aspx?m=131654 but don't really understand the last bit about queuing.

Has anyone got it configured and working please?

thanks