Support for importing The Recipe Box's .rbox files has been added on iOS as of Paprika v3.4.0. Make sure you have updated to at least this version before proceeding. Other file formats (e.g. .sqlite) are not supported for this app.
1. Open The Recipe Box and tap on the Email button.
2. Select File Export from the resulting menu.
3. An email will be drafted with an .rbox file attachment containing your recipes. Email this file to yourself and save it to your device.
4. Launch Paprika and go to Settings -> Import Recipes. Select the .rbox file for import and press the Import button.