Taxi from Hong Kong Airport to Regal Riverside hotel

From the airport to Sha Tin, you need to pay the taxi fee about 225 HK$ not including other additional charges. Your hotel is around the Sha Tin, but some distance from the center of Sha TinSo. So, at least, you need to pay 225 HK$ from the airport to your hotel, not including the additional charges.
I think the Hotelink Limousine is suggested, which is very confortable and cheaper than the taxi. You need to pay 150 HK$ for one person and this service includes the luggage service.
Or you can also take the bus A41 to get to Sha Tin and then change to a taxi, which is much cheaper than taking taxi from the airport to your hotel directly.

Michelle, thanks for your reply. I am traveling with my family of 4 person so look like taxi is still the cheaper option. But I would like to confirm the additional charges for Lantau link is HK 30 and each luaggage is HK 5 so the fare likely to be around HK 275 . Are I correct?

Yes, you are totally correct.