HTTP Redirect with Pool in iRules

Im not sure if I understand you correctly but you dont need any irule for that. 

Create your vs, create a pool with correct loadbalancing method (least connection is my recommendation but) in your case its roundrobin, attatch it to your vs and your good to go.

If you need that under an existing vs you could do this with LTM Policy (preferred over irule). Just create a new LTM Policy with condition "if host header is production.company.id forward traffic to pool Pool_sta"

and your Pool_sta need the correct loadbalancing method.