Help: Rebirth Macro for healbot

I have a Macro that im trying to work out to where it will announce my who i cast battle rez on....
It has taken me a lot of research and tireless trial and error to get to this far with it....

here is the macro

#showtooltip
/cast Rebirth
/run SendChatMessage("Casting "..GetSpellLink("Rebirth").." on %t!", ((UnitInRaid("player")and "RAID")or(GetNumPartyMembers()>0 and "PARTY")or "SAY"));

the "%t" is used to input the target players name into the text announcement.
Problem is since im using healbot to bind the macro, im not actually targetting the player. so then announcement comes up as follows

"Casting Rebirth on <no target>"
or whoever i happen to be targetting at the time (ussually a boss in a raid)

What i would like to know is is there is some sort of line i can put in there to actually retrive the playerID of the person that the spell is trargetting??

Thank you in advance!!!

PS i know there is an Addon called RSA that does all this and i would much prefer to use that addon, however i have downloaded this addon from multiple sources, multiple versions, and cannot seem to get this addon to work :(