export keyframes as a gif?

[lucykafka]

Is it possible to export just the keyframes as a gif? 
Or, when exporting gif, export every 5(th) or whatever frame — specific number of frames to keep down the gif size? (without changing the original file)

[lucykafka]

I think I figured out how to do this with Scale Spans — but I have to change the original file for this.  Would be nice to do this during "export as gif".