Connecting Mikrotik connection through a web proxy?

Hi… This is my simple network fro my home: Apple TV → Mikrotik → Internet.
I have a HTTP proxy with IP and port number.
I want to set up a proxy connection for the Apple TV box with mikrotik. Mikrotik will act as a web proxy client.
There are other devices that are connected to the router as well and I don’t want them to use proxy.
I had tinkering with IP/Proxy and IP/Firewall NAT settings to no success.
How to do this ?

Thank you