Suppose balance sheet of Thailand's central bank looks like this:

Assets Liabilities

FX reserves 200 Money 500

Gov't bonds 300

Then, the central bank intervenes in the foreign exchange market to strengthen the currency (the THB). The amount of the intervention is THB 100.

After the intervention:

Foreign exchange reserves are ["100", "200", "300"]

The money supply is ["400", "500", "600"]