Mazaika-Animation for MacOS — Output Movie
Output Movie Tab

Here, you can set up the size/resolution of the output video and add a text caption to it.
Video size - Select the video output size from several "popular" video sizes.
Height, Width - You can manually enter the video size here. Alternatively, you may resize the video display window to set up the output size.
Note: The main idea of the program is to grab content from the video display window and write it into the movie file. The size of this video display window is limited by your real computer display and your graphics card hardware. The video display window cannot have a higher resolution than your display. You may plug in a larger external display like an HD/4K TV set or computer display and move the video display window to that display. Alternatively, you may try changing the resolution of your built-in display. For example, if you use any modern Retina Display MacBook, you have an option to select "Scaled" resolution and set it for "More Space," which will give you much more display size.
Add Caption Check box - When checked, it will overprint the output video with a custom text caption.
Caption Text - Type the text caption here.
Press Export Movie Sequence button or select Export Movie... from File menu to start export.