How to change font size VideoFab Converter

Help, I am using VideoFab Converter to convert MKV to AVI with subtitle (.srt) embed to AVI output. But the output video got the small subtitle and hard to read.
Does anyone know how to change the font size? Please show.
Thanks in advance

Sorry Joe, this is not currently a supported feature.

Thanks Signals, I hope that VideoFab will put the little option to control the font size for the subtitle at the next version when there is a subtitle allow to embed.