Resellers have the ability to manage and add any custom proxy servers that have added for their users.
To view all proxies, you can click Proxies as shown below:
Here you can manage the custom proxy by selecting the LinkedIn account you want it to be added to:
Here you can add a new proxy for your users by pressing the button Add a new proxy:
Then you can fill in the information including the:
IP
Port
Username
Password
That's it! You're good to go.