Unfortunately I think you need to submit an RTSO.
I'm assuming the only reason to exercise a share option is if you'll make money on it, when you make money on share option you're liable to tax and need an RTSO.
The exercise price being the same as the market price is irrelevant for the RTSO, they most often will be the same when you exercise and sell immediately.
(If you decide to exercise a share option, but not sell immediately, then you still need to file the RTSO and pay tax within 30 days. When you do sell you'd need to pay CGT on any gain beyond the exercise price. But because the RTSO tax is due within 30 days in Ireland the almost everybody sells immediately.)