There are two ways to add an ink annotation in Xodo: from the quick tools menu and from the Annotation Toolbar.
Method 1
1. Long press on the document until the quick tools menu pops up.
2. Press Ink in the menu.
3. The ink toolbar will appear at the top of the screen. The ink toolbar contains an eraser and undo & redo buttons. You can scroll around the document using two fingers, or if you are using a stylus, only one finger. Click DONE to finish the drawing.
Method 2
1. Select Pens Toolbar. If you don't see the top toolbars, tap the center of your screen to bring it up.
2. Select ink tool.
3. The ink toolbar will appear with ink presets. You can navigate the document by using two fingers, or if you are using a stylus, only one finger.