Follow below steps to load balance citrix delivery controllers with netscaler:

1. Make sure you have snip configured in netscaler.
2. Create monitor using monitor type as citrix-xd-ddc. You can configure interval and time-out values if you need. Check validate credentials check box and enter your citrix site, service account credentials.
3. Goto servers option and add all your citrix delivery controllers there.
4. Click services option and create load balancing service for each delivery controller by specifying your servers from above step 3 and add monitor from step 2. If you have 4 delivery controllers, you have to create 4 services here. For port, enter your citrix server xml port. Default port is 80. To know your xml port, visit: https://www.knowcitrix.com/posts/change-xml-port-in-xendesktop-7-x/. Enter your xml port like 1234.
5. Create vserver. Make sure you update the same xml port here, as from step 4. Click “service and service groups” option and select all your services that you created in step 4. To the right, in persistence, choose cookieinsert type. This will make sure, only one dc is contacted over the whole application/VDA launch process i.e., for user authentication, enumeration, and application launch process.

So, basically you create a monitor, server, services (change port to your xml port)and configure all of them in virtual servers (change port to your xml port) option.