After Kithurst Hill, rolling trail passing through a car park at Chantry post. Go over the catle grid and follow the trail along the fence line to the left of the barn.
If you are feeling brave you can carry straight on to cross the busy A24. But I recommend a better route which goes through Washington (see Garmin route to the left), over a road bridge crossing the A24 and up the Bostal hill (not that steep) to meet up with the SDW.
After car park there is a steep-ish climb up towards Chanctonbury Hill. Some great views, then on towards Botolphs and a well-earned water tap on the corner before the road crossing. See below for 2 videos of this section
Water Tap: Before A24 crossing (not bridge route)
Water Tap: Botolphs corner before road crossing