By default the min res of the main container is set to 1024x600. However, this can be changed manually by editing the config.ini located in the same directory than NTKDBU.EXE - Just modify parameters of the 'MAIN' entry in the [WINDOWS] section.
Below is an excerpt of the config.ini generated by NTKDBU.exe for an 8" tablet with a 1024x600 screen res. In your case, you should just replace the entries 1024, 560 by 800, 600 (or even less)
Indeed, NTKdBU has been designed for Win32/64 platforms. Also, official tech support is for Windows only. However, the good news for U (and other Linux users) is that a couple weeks ago i've made some tests with the default Wine installed on my KUNBUTU box .... And ... i've been pleasantly suprised to run NTKdBU pretty well. i.e. run fast enough & stable. I've been able to use almost all database features/commands with great success. I've only encountered some minor problems with the visual interface. For instance: ClipBoard's not availble, Fonts used are not exactly similar, Bitmaps in the colNubs are not always displayed, couldn't drag, nor resize the datagrid's columns with the mouse using the nubHeadings gadget (probably some notification messages of the Win32 API that are not yet supported under Wine), etc. Frankly speaking, nothing really difficult to overcome in order to use main features of the software.
But once again, NTKdBU under Linux is not officially supported by the NTK Team. It's my own experience - So, if you try to do the same, just use it as is and at your own risks.
Below some screenshots: Main ListView
Data Entry - Detection of concurrent access in network environment
I have no particular recommendations since NTKdBU under Linux is not officially supported. However and FYI, I personally use an old UBUNTU 10.10 + KDE 4.5.1 + Wine 1.2.2. BTW, I didn't make any specific settings - just use Wine with its default configuration. i.e. Win XP optimization.