To create a SmartPDF asset, please use the Asset Packager.
Once you have the Asset Packager installed, run it and create an [PDF] asset type. Give it a name for the shelf title, select your previously created PDF and an asset thumbnail, then click the [Create Asset] button.
This will generate a .zip file, which is your asset. There are a few more tweaks to convert it from a PDF asset to a SmartPDF asset.
Locate the .zip file on your system, and unzip it. Replace the complete ‘content’ folder with the ‘content’ folder that you have previously put together for the SmartPDF asset. Re-zip the asset (on the same folder that you have unzipped it).
This new .zip file is now a SmartPDF asset.