
I'd avoid the Bisto for a start as it contins salt which Flynn doesn't need and adding little extras to tempt him encourages fussiness, IMO. The dog learns to ignore the bowl of plain kibble as, if he waits long enough, something tasty will be added. Dogs are excellent at training us given half a chance ;)
You could try heating the bowl of kibble gently in the microwave (10-20 seconds) as the heat helps to release the aroma from the food and make it more enticing to the dog. My dogs never really liked kibble with hot water added either but the microwave trick worked for us :)
Otherwise, just keep putting his bowl down at regular meal times. Lift the bowl after 15 minutes whether he has eaten or not. Feed nothing until next meal time (no chews or titbits) and repeat. A healthy dog will not starve itself for long. Some dogs are stubborn and can carry this on for several days (my pup did) but perseverance is the key. Helathy dogs can easily survive without food for many days, as long as they have access to plenty of fresh water.
Also, at 6 months, he may be ready to go down to 2 meals per day? Not sure about little breeds but this would be about right in larger breeds.
*edited*...I see Mel beat me to it :)