Put the HTMLArticlePackager on left side bar of Finder, under Favorites.
Then, just drag and release the folder that you intend to convert over the App name at left side bar on Finder.
Maybe it could help
:: Add an item to the Finder Favorites section:
Drag the file or folder to the Favorites section of the Finder sidebar.
To add an app, hold down the Command (⌘) key while you drag.