On is handled with the -Daq suffix: raSDaq 'oHtaH quS'e' The chair is on the table.
Although notice that it includes some ambiguity: this could also mean The chair is at the table. If you absolutely had to make the distinction, you could say raS yorDaq 'oHtaH quS'e' The table is on the top surface of the table and raS Daq 'oHtaH quS Daq'e' The chair's location is the table's location. (Daq is a separate Klingon word meaning location.)
(The final glottal stop is also not aspirated properly.)