This Tutorial is for Nodekit Version 0.7.5. In the current version, the screen shot size is exactly the size of the screen resolution and there is no way to change this.
Tutorial for Nodekit Version 0.7.3 and 0.7.4
You can make screenshots of your current scene in TIF format by pressing the combination of buttons 7+8+3 on the gamepad (visualised with a white flash). They'll be saved in “My Documents\Nodekit\Tagtool Images”
To change the size of the screenshots that will be saved:
Step 1 - locate the Screenshot node all the way in the North-East of the Tagtool patch, right next to the “welcome-node”.
Step 2 - Enter the Width or Height you require (the other value respectively will be changed according to the aspect ratio). Or enter a keyword in the size field: “small” (1024×768), “medium” (2048×1536), “big” (4096×3072) or “huge” (8192×6144). Keep in mind file size will increase with screenshot size (make sure you have disk space for multiple huge files). The small is approx. 150KB, the medium approx 750KB, the big approx. 2MB and the huge is approx. 6MB per screenshot.
Note: This does not increase the area of the screenshot just the resolution. What size to use depends on what you plan to do with image - printing on paper or posting online or ???.
(The full instructions for using the gamepad can be found here)