Views:
To include a product on the packing list, check Box on Product when entering an Order.   Then select one of the print options.

Explanation:  A packing list shows order information without any pricing or cost.  Defaults can be set in Company Setup for your preferred Send Method, Email, and Instructions for the packing list form.  
 
 
If you would like this product to print on the Packing List you must click the "Include on Packing List" checkbox.  The default is to not print.

System Preferences has an Order Preferences setting allowing you to ‘Include all products on packing list’.
 
 
This option follows the similar logic of the same question within the program resource, if you use expanded inventory, including that it will not affect additional charges and will affect freight lines. 

If the setting is checked, all new lines added to quotes/orders will default as checked to ‘Include on packing list’, unless the order contains a program. If an order contains a program, the setting from the program will take priority. 

Order imports will only use the System Preference setting if there is no program in the file and the product in the file has no <IncludeOnPackingList> node.

Expanded Inventory Only:
If there is a program set up, you can check to Include all products on packing list within the Program - Other Expander