Return on national principal equations

Hi guys

Could you please help me with Return on notional principal for both fully collateralized and partially collateralized , I don’t know how to implement it on the calculator

I stuck in LN function , how can I put it into the BA I calculator

the formulas are

Fully = LN(1+R) + Rf

Partially = [L * LN ( 1+R)] + Rf

thanks for your help and time

If R is say 8% and Rf is 3%.

Then for Fully, the keystrokes would be…

1.08 LN + 0.03 = 0.10696