Annotator is a handy tool that helps creating annotation files for a collection of images.
Place all images you want to annotate in a folder of your choice. Open Annotator and browse to the image folder.
Use the Previous and Next buttons to navigate among image files. Use the mouse to create rectangles in every image. Place the mouse pointer over a rectangle to select it, use the handles to edit it. Press Delete key to remove a selected rectangle.
By default annotations are saved in the same folder as images in a XML file named Annotation.xml. Export menu option creates a TXT annotation file.