This is a new version of the Manage Feed page, introduced in ProGet 5.3. If it's missing any functionality, you can still use the old version.
A NuGet feed in ProGet may be configured as a Symbol/Source server compatible with debuggers such as Visual Studio and WinDbg. See the Symbol and Source Server documentation for configuration instructions and restrictions.

Symbol & Source Server Properties

Strip symbol files Disabled
Strip source code Disabled
Remove signature file Disabled