Access remote SFTP file server using SSH key pair authentication

Hallo All,

We do have the following requirements. We need to share some CSV exports from the Kiwa Appian environment to a remote file server using SFTP. However, the SFTP file server must be accessed through an SSH key pair.

I'm trying to use the "SFTP Functions" plugin from the Appian marketplace. Since we need to use the SSH key pair to access the remote file server. I was looking Appian community for help and found the following discussion thread useful and tried to follow the instructions.

Appian Community

But to proceed further, I have a few questions about the shared approach and need your support on this.

1. Is it possible to communicate SFTP file server using SSH key pairs from Appian? Could you please share any Appian documentation for this?
2. In the discussion, It mentioned that I need to configure third-party credentials, could please mention what will be the credentials field names and values?
3. I tried to configure third-party credentials with "username" and "password" fields,
   1. The username is the user name to access the remote server
   2. I tried to set the password value as the private key. Since the length of the private key is 3330 characters. Appian does not allow more than 2500 characters. 

Is it the correct approach? If yes, Please help me to set the password field with our private key.

Thanks