The Canadian version of Rad DK has the following features:
Selecting an isotope: to use the calculator's equations you need to first select an isotope. Find the isotope on the list and click it to select it. The isotope's half-life and Canadian regulatory information will be displayed.
If your isotope is not on the list: all three of the decay equations on this calculator require the selected isotope's half-life which it gets from the Half-life textbox at the top of the screen. If your isotope is not on the list, you can still use the equations. Find out the isotope's half-life and enter it in the Half-life textbox at the top of the screen along with the appropriate time units (s, m, h, d or y) in the small textbox to the right. You can get half-life values here. If the half-life is in exponential form you may enter it either as (e.g.) 1.2E4 or as 12000. Note that 12000 and 1.2E4 have 2 significant figures each, while 12000. and 1.2000E4 each have 5. See the discussion on significant figures for more information.