As of WriteMapper 1.1.0, you can link images in your WriteMap from the editor view.
To do so, simply select either the "Link Image File" or "Link Image URL" options from the toolbar, and you'll be prompted to choose a file destination or enter a URL, respectively. Once you've entered that information, the image will get displayed in the editor.
The RTF and TXT file formats do not support images, and as such, any images exported to these two file formats will simply appear as a single line of text, with their source locations enclosed within square brackets, e.g. "[https://example.com/test_image.png]"
Any images from URLs exported to the DOCX file format will require a working internet connection in order to have the images properly downloaded into the DOCX text document.
Do also note that the images are linked to from their original location, so if the images are removed in your file system or from the URL you originally provided, the image may not successfully display in the editor.