For both Magento 1 and Magento 2, it is possible to include the stock percentage in the feed. This option allows an additional attribute, 'stock percentage,' to be added in the export, indicating the availability of the product across all different sizes (simple products). A percentage of 100% indicates that all sizes for that product are available. A percentage of 50% indicates that half of the sizes are available.
Magento 1
Navigate to the Tweakwise Export module (System > Configuration > Catalog > Tweakwise > Export). To include the stock percentage in the feed, set the following setting to 'Yes'.