To add annotations into flash flipbook, you may use Boxoft PDF to Flipbook Pro
Here are steps in detail to add annotations:
Step1: Open Boxoft PDF to Flipbook Pro, and then import PDF from your computer for conversion;
Step2: Click “Edit Pages” button in top toolbar panel to enter into “Flip Page Editor” interface;
Step3: Click “Select Text Displayer to Insert” button to draw a shade area on flip page;
Step4: Set “Text Properties”