You will need to know the number of preference shares issued and the dividend that is accumulated every year. For example, if a company has issued 10,000 11% preference shares, then the dividends paid for preference shares are : 10,000 * 0.11=1,100
If you don’t have access to such information, you can try to find the statement of financial position. The total dividends paid should be included in the statement of changes in equity. Then, you can find details for the dividends and the preference shares in the notes.