Which is the most early type star with a planet discovered by radial velocity method? We have discovered planets in  Beta_Pictoris(A6V)here and Fomalhaut alpha(A3v)here. 
However they were discovered by direct images.

There should be an stellar type limit by RV?  
What is the most early type ever found?
HD 103774 b, detected by radial velocity, orbits a star of spectral type F5V according to The Extrasolar Planet Encyclopeadia.

HD 102956 b, detected by radial velocity, orbits a spectral type A subgiant, the star of the "earliest" type harboring a planet detected by radial velocity, I could find (as of May 2014).

The entry for
Kepler-88 c around a spectral type B star (according to the catalog as of May 2014) appears to be incorrect, or encodes something else, the star should be classified as spectral type G6V.