Description
Setting this option allows you to specify a Form JSON file from which a set of default forms can be pre-generated when a new site is created on your Multisite install.
Usage
define( 'GF_IMPORT_FILE', 'http://www.domain.com/path/to/gf_import.json' );
Placement
This constant should be set in your wp-config.php. See the article WP Config Options for more details regarding the JSON file.