How to communicate with On-premise Postgresql Database from Azure data factory

Can we connect source as on-premise postgresql database and then do mapping data flow transformations in Azure data factory. Once done send the transformed data back onto On-premise Postgresql database.

I am not sure why, but azure is not allowing me to select on-premise postgresql as linked service in the mapping data flows . Can you please guide me with this issue. I am not able to find any source on Google w.r.t this.

You can see that Postgresql option is blurred.