reduce file size

I have a video 1280 x 720 and 34 mb.
All I want to do is a a logo to the video

when I export/ share to master file the size is over 200mb when choosing H:264 ?

The png logo image I've added is only 44kb so I'm not sure why it's so big ?

I'm new and can't figure this out

Thanks in advance

When using H.264, file size is a combination of duration and data rate. Since you're not going to change the duration, data rate is the variable. Lower data rate, lower file size but also lower quality. Such is the nature of lossy codecs. For post production use in another program you'd want to export Apple Pro Res and that is going to be a relative large file but near visually lossless depending on the flavor of ProRes

Thanks

I just want to be able to add a small logo watermark and keep the video size simialr but it doubles or triples it which I find odd.

Export data rate controls file size.
Changing content has very little effect.
Sorry but the logo has virtually nothing to do with the exported file size.
Project size is another story. Adding media can certainly increate the project (library) size.
Again that has virtually NOTHING to do with exported size of the H.264 .mov (or mp4) or ProRes .mov