The below documents are required:
1. Passport/travel document with blank pages and a validity of at least 6 months.
2. One completed application form affixed with one passport-sized photo.
3. Philippine nationals who desire to stay in HK for more than 14 days, shall present an invitation letter in which the sponsor agrees to provide financial support and accommodation, and one copy of the sponsor's HK ID.

it costs 1600 pesos

Thanks for the reply. However I have another query. Where would I submit the forms?

And one more thing sir, is it possible that my application for an extended visit be denied? What are the chances that it will be?
My father who is an engineer and has been staying in Hongkong for a long time will be the one sponsoring my application.

You can submit your visa applicaiton to the Consular office of the Embassy of the People's Republic of China in the Philippines in person or through an authorized travel agency. Applicants may also make the application directly to HK Immigration Department.
generally, you will be issued a visa to HK if you provide what they required.

Sir, one last thing, how long will it take for the processing of my application?

The processing takes about one month if your applicaiton will be sent to HK Immigration department for approval.