AcuteFinder now has a built-in file viewer, that can be used to view images, text files, RTF-documents and contents of archive files (list of files). You can activate this viewer in various ways: By selecting Auto-view on the toolbar; by choosing View file from the popup-menu or toolbar. Most importantly, you can select the size and position of the Viewer window. For example, if you have a big monitor, you can use it to view images full-size.
When selecting files to be acted upon, you can view each file automatically as you select it. Just check the Auto-view checkbox and configure the Viewer settings as needed.