Not really recommended. You would be better using an Ericaceous feed.

Bone meal is pretty useless as a feed for almost anything - unless its been fortified with added nitrogen, it just contributes calcium and phosphorus to the soil, and takes years to slowly break down. Even the phosphorus content is unable to be accessed by plants growing in soils with a ph of 7.0 or less. Usual NPK, if its fortified is around 3-15-0.

A much better choice is fish blood and bone - usual NPK 5-5-6.5, for actually feeding plants, but with an azalea, agree with Owdboggy - I'd stick to ericaceous or just use Growmore.

My Azaleas seem to like Sequestrine . . .