I have now a BLUE COAT SG200 Web Proxy.
Now I need some help to configure the RB1200, as I'm going to have two uplink WANs and I want to connect the SG200 to two ports of the RB1200. So the traffic from the WANs should go out on one port to the SG200 and coming back into the RB on a other port. Then the traffic should be routed to the other ports of the RB, which I used for the client equipment.
What is the best way to configure that in RB?
How to seperate the traffic in a right way?

Thank you for your help.

It should look like attached:

No one has a hint for me?

I am not so familair with blue coat only with squid web proxy.

usually with squid you can have 3 lans of routerboard to make the whole thing work. if blue coat is web proxy, it might work as well.

lan 1 = wan (internet)
lan 2 = proxy machine
lan 3 = users pppoe or hotspot

just setup few firewalls and NAT and i believe everything should work fine.