You can specify multiple source IP's in the outbound VPN firewall policies. Looks like you're not entering the IP address correctly (from your screenshot). Each IP must be separated by a comma. See below:
Thank you General-Zod, But I think my question was wrong, i need to make a bunch of the subnet in source IP. somthing like 192.168.3.0/24,192.168.1.0/24,192.168.4.0/24.................