"On your table" would be "(senin) masanın üzerinde." It's spelled the same, but it's constructed differently:
- "the table's" = masa+nın (masa + genetive suffix "-(n)ın" including the "n" buffer letter)
- "your table's" = masa+n+ın (masa + possessive suffix "-(ı)n" for sen without the "ı" buffer letter + genetive suffix "(n)ın" without the "n" buffer letter)
For siz, "on your table" = "(sizin) masanızın üzerinde" (masa + (ı)nız + (n)ın)
It is actually the most correct grammatical form. But in practice, we skip -dir, dır most of the time. Since we skip it, it might mean slightly different when you use it. It adds a spice of "probably" when you add it in the daily speech. Like "-Anahtarlar nerede? +Masanın üzerindedir." "-Where are the keys? +They are (probably) on the table."