You have obviously misread the PDF. The housing allowance is NOT taxed at 16%. Nor is the expense regarded as deductible. Whatever the amount of your housing allowance, provided that your employer "execrises proper control" that you do actually spend it on housing (i.e. they should keep copies of your rental agreement and monthly receipts on file) then a taxable value of 10% of the remainder of your salary package is added to your salary for tax purposes. Any portion of your "housing allowance" which is NOT spent on housing is taxed as income in the normal way.
The actual tax you pay on any level of income is a sliding scale up to a maximum flat rate of 16%, which you hit on annual income of about HK$1M. The Inland Revenue has a tax calculator here:
http://www.ird.gov.hk/eng/ese/st_com..._07/stcfrm.htm but this does not deal with housing, whose taxable value you need to calculate as per the PDF.