is there a formula that he uses to allocate weight???

Yes there is, well sort of .... See my next few posts.

There is handicapping policies in each state. But the handicappers do get some subjective input.

Here are a few links ...

racingvictoria.net.au/index.php?option=com_content&task=view&id=114&Itemid=16
Check out the PDF's on handicapping policy

racingnsw.com.au/page.asp?parm=han.main
Check out the links on the left - There is a Handicapping policy

waturf.org.au/etc/pics/2007_RBH_Template1.pdf
PDF on ratings vs weights.

racingsa.com.au/racing/pdf/SARatingsTempleplate.pdf
SA Ratings vs weights

risa.com.au/Rating_Based_Info.asp
A good page to check the rating of the horse.

Or you could just search google for "Handicapping policy".

Obviously each state has a different handicapping policy.

Good Luck.

obviously these are the starting points and the handicapper does have some subjective input into the race.

A good page to read about it is ausrace.com/art/handicapping.htm

Good Luck,