Hi Mark. CEF attestation papers say Keiller was born in Scotland in 1886. Joined in Toronto with the 198th Battalion CEF, serving with the 75th Battalion when killed.
CEF papers:
http://www.bac-lac.gc.ca/eng/discove...dNumber=490272
[click the "Digitized service file - PDF format:" to see his whole personnel file] (slow download, but worth it)
CWGC has him buried in Beaucourt British Cemetery (near the Somme, 18km SE of Amiens).