You definitely need equal signs in the conditionals...
Code:
<select name="set_class1" id="set_class1" value="{vb:raw rkc_variable.class_1}">
<option value="">Choose Class</option>
<option value="ClassType1"<vb:if condition="($rkc_variable1['class_1']='ClassType1')"> selected="selected"</vb:if>>ClassType1</option>
<option value="ClassType2"<vb:if condition="($rkc_variable1['class_1']='ClassType2')"> selected="selected"</vb:if>>ClassType2</option>
</select>
If that gives you an error try it without the single quotes around 'class_1' - sometimes they don't work right in templates.