I want to create a connection string from SSRS to Vertica using Datasource

You need to do it via User Interface. Please check the below link. Where are you planning to use the SSRS connection string?

https://www.vertica.com/kb/Vertica-QuickStart-for-SSRS/Content/Partner/Vertica-QuickStart-for-SSRS.htm

Hi Sruthi
Thanks for the update, I was able to create the SSRS report as you specified, But when i want to deploy the report I want to create a datasource from with in Report Server URL, Driver={Vertica}; Database=XXXX; Servername=XXXXX; UID=XXXX; PWD=<>; PreferredAddressFamily=none; like this not able to do it.