Interesting design. I'm trying to figure out what your plans are though.
I assume the drop fertilizer spreader will tend to spread seeds evenly. Which isn't a problem if that is desired, for grass or a grain.
Your baler/rake tines scratch the dirt in rows, but don't really force the seeds into a row, nor cover very many of them.
If you wish to drop the seeds evenly, then cover them slightly, you might consider dragging something behind such as a 4x4, chunk of steel, some chain, fencing, or such.
It is being used on tilled ground?
I saw this on craigslist.
5' Vineyard Seed Drill
It is on the West Coast, but it may give you some ideas. Old grain drills are cheap, although, not always functional. This one apparently was cut in half for use in an orchard, but may be a more manageable size for a small plot.