Question: For scrip Dividends/Re-invested Dividends
Updated Answer: This is now the recommended approach
Question: Bonus shares/free shares
Answer: You can simply enter a buy transaction at price SGD 0 (on the date the shares is given) and maybe add a note to yourself for clarity.
(Although StocksCafe will give you a warning by visually highlighting the price in red, it is fine to ignore it. It is there just in case you have made a mistake in entering the price.)