How to create an indicator of the percentage Change difference between two products?

I like to use spread trading between HKEX.HSI And HKEX.HHI.
I used the Spread-Diff indicator to calculate the real spread between 2 products.
But i want the percentage Change format as well.
For example, the HKEX.HSI is increasing 1.5% and the HKEX.HHI. is increasing 1% only,
The spread of percentage change between two products is 0.5%,
I try to modify the original spread diff indicator to do it but failed.
How can i create an indicator to do it? Thanks!!

Yeung0510,

what exactly did you try as modification of the original spread indicator?
The default indicator uses the raw price input, but you can freely customize the inputs and could provide a formula instead that computes the percentage change for each symbol.

Regards,

ABCTG