create lookup field as feature

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hi all,
i have one custon list called "Guest" List
i want to create one site column ( lookup filed ).. we can do in site
column and create ..then it fine..

but how we need to craeted lookup filed as feature.
i ceated... feature.xml and element.xml files.
in element.xml files

<Field Type="Lookup"
DisplayName="Guest"
Required="FALSE"
List="Guest"
ShowField="Title"
UnlimitedLengthInDocumentLibrary="FALSE"
Group="Custom"
ID="{99C3AA22-B372-4427-A94B-01B01C28AC89}"
SourceID="http://schemas.microsoft.com/sharepoint/v3";
StaticName="Guest"
Name="Guest"
FieldRef="ID"
/>

in in List attribute if i give list Guid id.. it's working perfect but
if i give list name is not working,.. the list guid changes site by
site or site colletion .. how can i do.. plz help meee..

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