Best Model for comparing R&D Spending to business performance metrics

#1
I am currently doing a Study on R&D spending vs business performance metrics to see if I can prove for x spending on R&D = x increase in Gross Profit, EPS, EBITDA, and Net Profit.
I have data collected from 40 businesses that publish R&D spending over 11 years on all the above.
I have been using R&D as the independent variable and the remainder as dependant variables.

Correlation is showing significant at the following levels:

RD EPS NP EBITDA OP GP
RD Pearson Correlation 1 .572 .581 .496 .489 .671
Sig. (2-tailed) .000 .000 .000 .000 .000
N 440 440 440 440 440 440

The linear regression results are poor.

PP Plot is snakes on either side of the line.

I have read I may need to perform root testing to make these variables stable, first. How do you do this in SPSS?

Any other ideas on how to achieve my aim would be much appreciated. Hours on youtube self-teaching I have confused myself!!