The matter of signing the paintings has always been problematic to me. I do not like to disturb the surface without careful consideration first and at best find the act of signing something uncomfortably self-conscious. Sometimes this is not the case. My latest idea is to make a handprint on the back of the work to reference the hand-made nature of the painting. A handprint is a general signature but also an individual one, like modern day fingerprinting the print is unique to me. I am conscious of being inextricably bound up in the work.
The handshapes left behind on cave walls by our early ancestors were not prints, therefore not individuated. It is thought that these marks were produced by stenciling; the pigment blown onto the back of the hand with the hand placed on the wall to act as mask, leaving the hand shape clearly distinguishable. For images of this go to this link
Concerning the self-consciousness of the act of signing a work, I remember a story about Michelangelo:
for a close up of his signing see this link
According to Giorgio Vasari, shortly after the installation of his Pietà, Michelangelo overheard (or asked visitors about the sculptor) someone remark that it was the work of another sculptor, Cristoforo Solari, whereupon Michelangelo signed the sculpture.Michelangelo carved MICHAELA[N]GELUS BONAROTUS FLORENTIN[US] FACIEBA[T] (Michelangelo Buonarroti, Florentine, made this) on the sash running across Mary’s chest. The signature echoes one used by the ancient Greek artists, Apelles and Polykleitos. It was the only work he ever signed. Vasari also reports the anecdote that Michelangelo later regretted his outburst of pride and swore never to sign another work of his hands.