Relayd forward matching Host header to different port

[Mike Casinghino]

I am trying to configure relayd on 7.6 to forward http traffic to a different 
port on 127.0.0.1 based on the Host header. For example, I would like to do:

table <localhost> { 127.0.0.1 } 
http protocol "https" {
    tls { keypair "example.com" }
    match request header "Host" value "app1.example.com" forward to <localhost> 
port 9991
    match request header "Host" value "app2.example.com" forward to <localhost> 
port 9992
}
# Terminate tls and proxy
relay "tlsproxy" {
    listen on egress port 443 tls
    forward to 127.0.0.1 port 8000
    protocol "https"
}

I am getting a syntax error on the match request lines because of the port 
specification. As far as I can tell, the match rule doesn't support a port 
number nor does the table definition. Any advice is appreciated