I am the one who actually ported PureEdge and Lotus Forms for Mac. As for resizing the window you need to use the screen size controls that are native to the program. You can access the control from the bottom right of the window. Click-Drag (It's actually very easy, and allows the program to look like it belongs in a Mac environment) You can also remove decorations through the program, but it will look like a win98 gui.
Unfortunately several sites have repackaged this program, omitting the original readme. Regardless, Lotus Forms V4.0 and higher is more stable in OSX. I have made available a new version based on Lotus Forms Viewer 4.0.0.3 which will allow you to view, edit and print like before. The major difference is that the new version does not have or need Java to function. There are some drawbacks to this with newer forms but they will still load and can be modified.
The latest version can be downloaded here: http://aeonconcepts.com/lotus
Please Note: Unless drastic changes are made to revised forms that break functionality of this version, this should be the last release required. If future OSX versions break the functionality, an updated version will be released.