Make a capsule item for example:
<capsule itemId="8659"> <!-- RB BOMB ITEM ID -->
<item id="8660" min="1" max="1" chance="10." /> <!-- here put RB -->
<item id="8661" min="1" max="1" chance="10." />
<item id="8662" min="1" max="1" chance="10." />
<item id="8663" min="1" max="1" chance="10." />
<item id="8664" min="1" max="1" chance="10." />
<item id="8665" min="1" max="1" chance="10." />
<item id="8666" min="1" max="1" chance="10." />
<item id="8667" min="1" max="1" chance="10." />
<item id="8668" min="1" max="1" chance="10." />
<item id="8669" min="1" max="1" chance="10." />
</capsule>
So when they double click they will get a random rb.