[iPhone] Marker Felt font

I am trying to draw text using the Marker Felt font, which various sources claim is available on the iPhone. I've tried using "MarkerFelt", "Marker Felt" and "Marker-Felt", but no text shows up. The same code works if I specify "Helvetica":

CGContextSelectFont (gc, "MarkerFelt", 18, kCGEncodingMacRoman);
CGContextSetTextDrawingMode (gc, kCGTextFill);
CGContextSetRGBFillColor (gc, 1.0f, 1.0f, 1.0f, 1.0f);
CGContextSetRGBStrokeColor (gc, 1.0f, 1.0f, 1.0f, 1.0f);
CGContextShowTextAtPoint (gc, 38.0f, 10.0f, text, strlen(text));