You should be able to go to your Alt-F web page, go to Packages > Alt-F, and as long as you have a valid feed configured and enabled (on the top 'Package Feeds' section, such as "
https://downloads.sourceforge.net/project/alt-f/pkgs/stable"), you should be able to scroll down in the 'Available Packages' section, find 'netatalk' and press the Install button to install it.