Not the complete process but once you have annotated the PDF in Preview save it to a Hazel monitored folder and create a Rule using this script, it will attach the file to an email and send to your nominated recipient. You can then have an additional Rule to either file the PDF away or delete it if no longer required.
Hope its helps
Iain
set theAttachment to theFile
tell application "Mail"
set theMessage to make new outgoing message with properties {visible:true, sender:"your email",subject:"subject", content:"Content\n\nSignature" & linefeed & linefeed}
tell theMessage
make new to recipient at end of to recipients with properties {name:"recipient", address:"johndoe@domain.com"}
end tell
tell content of theMessage
make new attachment with properties {file name:theAttachment} at after last paragraph
end tell
delay 1
send theMessage
end tell