I think you're referring to the following documentation:
https://docs.citrix.com/en-us/netscaler-gateway/12/rdp-proxy.html 

Citrix NetScaler Gateway 11.1: Needs to integrate Microsoft RDS from gateway
https://www.thomaspreischl.de/citrix-adc-as-rds-gateway-with-rds-broker/ 
We are able to enumerate the apps now by adding them as the bookmark.
Issue :- Unable to find the connection  details in RDP Connection.
Per the article :-  https://docs.citrix.com/en-us/netscaler-gateway/12/rdp-proxy.html.
 followed the configuration
Even added the host FQDN under client profile ,  but still don't get the connection information.

For 11.1 take a look at this:

https://blog.ollischer.com/citrix-netscaler-v11-how-to-setup-your-netscaler-as-an-rds-rd-gateway 

https://www.carlstalhood.com/netscaler-gateway-11-rdp-proxy/ 

Thank you Jazz Kaur.
Now we configured the Citrix NetScaler Version 11.1 as an RDS RD Gateway. But it's not working as Reverse Proxy.
i.e using 443 app launching is not working. If I open 3389 at Firewall side, then It's working.
Any suggestions?

That’s strange, this was all I could find similar to what you stated. Perhaps it is something with the firewall rules.
https://support.citrix.com/article/CTX228470

We may need to allow the applications like Ms-rdp, Ssl, Cotp, T.120 in firewall rules to allow this traffic.“

We know that, RDP Port 3389 won't allow over Internet.
Security team never accept.
Any other way to solve this issue?

I would suggest examining the load balancing, there are some suggestions here to fix the reverse proxy configuration:

https://discussions.citrix.com/topic/402138-netscaler-reverse-proxy/

and

https://discussions.citrix.com/topic/405953-netscaler-reverse-proxy/

Documentation:
https://docs.citrix.com/en-us/citrix-adc/13/citrix-adc-cache-redirection-gen-wrapper-10-con/cache-redirection-config/configure-reverse-proxy-redirection.html?_ga=2.217797270.1457101011.1594662766-399648896.1594088851

Issue with RDP reverse proxy. Other Citrix apps and VDI's are fine.
Till facing issue with RDP reverse proxy.
Please suggest.

I’ve reached out to fellow Experts to assist with the remaining issue.

Hi Murty M,

Review the following linked article guide below — can you re-verify your settings again (you’ll see a 443  configuration example towards the bottom as well) to compare against:

Configure RDP Proxy in NetScaler

A further article from Carl Stalhood.

https://www.carlstalhood.com/netscaler-gateway-12-rdp-proxy/ 

Also Citrix Forums - https://discussions.citrix.com/topic/404362-netscaler-gateway-for-rds-farm/