It's still unclear whether you have followed up the link to the Q&As Herman kindly provided.
What do I need to give as Evidences to the Appeal ?
Well, it depends what sort of case you wish to present.
Firstly, if you're arguing against oversubscription, you should have found the typical reasons given in the Q&As:http://www.elevenplusexams.co.uk/appeal ... -school#c2
- but only you can say which of these reasons would apply to your case.
Depending on the reasons, there are some examples in the Q&As of the sort of evidence that might be appropriate.
Secondly, bearing in mind that score is used in the oversubscription criteria, if your daughter underperformed in one particular part of the 11+ (let's take maths as an example), then it might help your case if you have alternative academic evidence to show that she is really good at maths and could reasonably have been expected to score much more highly than she did! Evidence might include some of the following:
School reports showing excellent progress in maths,
top set for maths in a high performing school,
5a prediction for maths at Key Stage 2,
gold certificate in primary maths challenge,
Gifted & Talented for maths,
Again, it depends what sort of case you want to present.