He, without a doubt, pencilled them and signed them. Who inked them is another question wich remains open to debate. The panels below are taken from the final two weeks of "Bleak Prospects" (May 31 to June 12, 1948), IDW Rip Kirby vol 1, pages 256 to 259.
See how different the inking is compared to the style with heavy brushstrokes normaly used around this time. ( Even the lettering is different on these strips. ) The style reminds me of the work of Russell Patterson. Could it be him helping Raymond out? Or is it Raymond himself testing another style? Guess we'll never know.
Speaking of Alex Raymond and inkers. The weeks leading up to these final two weeks of the "Bleak Prospects"storyline are also inked by someone else than the regular inker. In that case I'm pretty sure who the ghost inker is.
Looks like Frank Godwin, doesn't it. :)