"How to get the attribute relevance using SVM"

Hello,

I have a SVM Model (LibSVM because of multiclass problem) (included in X-Validation) and I want to know, which attributes are most relevant. I already did a grid search to find out the best parameter combination of gamma and c.
Can I get the attribute relevance with a RBF Kernel or do I have to use a Linear Kernel?
How can I get the information and where would i have to put an additional operator?

The process code is attached. Thanks for your help

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<process version="5.3.015">
  <context>
    <input/>
    <output/>
    <macros/>
  </context>
  <operator activated="true" class="process" compatibility="5.3.015" expanded="true" name="Process">
    <process expanded="true">
      <operator activated="true" class="retrieve" compatibility="5.3.015" expanded="true" height="60" name="Retrieve Master Excelliste_Gefügebezeichnung_3 klassen" width="90" x="45" y="30">
        <parameter key="repository_entry" value="../../Data/Master Excelliste_Gefügebezeichnung_3 klassen"/>
      </operator>
      <operator activated="true" class="normalize" compatibility="5.3.015" expanded="true" height="94" name="Normalize" width="90" x="179" y="30">
        <parameter key="method" value="range transformation"/>
        <parameter key="min" value="-1.0"/>
      </operator>
      <operator activated="true" class="split_validation" compatibility="5.3.015" expanded="true" height="112" name="Validation" width="90" x="380" y="30">
        <parameter key="split_ratio" value="0.8"/>
        <parameter key="sampling_type" value="stratified sampling"/>
        <process expanded="true">
          <operator activated="true" class="support_vector_machine_libsvm" compatibility="5.3.015" expanded="true" height="76" name="SVM" width="90" x="150" y="30">
            <parameter key="gamma" value="0.03087"/>
            <parameter key="C" value="898910.0"/>
            <list key="class_weights"/>
          </operator>
          <connect from_port="training" to_op="SVM" to_port="training set"/>
          <connect from_op="SVM" from_port="model" to_port="model"/>
          <portSpacing port="source_training" spacing="0"/>
          <portSpacing port="sink_model" spacing="0"/>
          <portSpacing port="sink_through 1" spacing="0"/>
        </process>
        <process expanded="true">
          <operator activated="true" class="apply_model" compatibility="5.3.015" expanded="true" height="76" name="Apply Model" width="90" x="45" y="30">
            <list key="application_parameters"/>
          </operator>
          <operator activated="true" class="performance" compatibility="5.3.015" expanded="true" height="76" name="Performance" width="90" x="248" y="30"/>
          <connect from_port="model" to_op="Apply Model" to_port="model"/>
          <connect from_port="test set" to_op="Apply Model" to_port="unlabelled data"/>
          <connect from_op="Apply Model" from_port="labelled data" to_op="Performance" to_port="labelled data"/>
          <connect from_op="Performance" from_port="performance" to_port="averagable 1"/>
          <portSpacing port="source_model" spacing="0"/>
          <portSpacing port="source_test set" spacing="0"/>
          <portSpacing port="source_through 1" spacing="0"/>
          <portSpacing port="sink_averagable 1" spacing="0"/>
          <portSpacing port="sink_averagable 2" spacing="0"/>
        </process>
      </operator>
      <connect from_op="Retrieve Master Excelliste_Gefügebezeichnung_3 klassen" from_port="output" to_op="Normalize" to_port="example set input"/>
      <connect from_op="Normalize" from_port="example set output" to_op="Validation" to_port="training"/>
      <connect from_op="Validation" from_port="model" to_port="result 1"/>
      <connect from_op="Validation" from_port="averagable 1" to_port="result 2"/>
      <portSpacing port="source_input 1" spacing="0"/>
      <portSpacing port="sink_result 1" spacing="0"/>
      <portSpacing port="sink_result 2" spacing="0"/>
      <portSpacing port="sink_result 3" spacing="0"/>
    </process>
  </operator>
</process>