Internet - If there isn't a date

If there isn't a date when the webpage was created or updated, then you can put (n.d.) in the citation and (no date) in the reference list.

In-text citation:

SportEx Medicine (n.d.) identify the acronym PRICE to remember to Protect, Rest, Ice, Compression and Elevate the affected limb following soft tissue injury.

PRICE is a useful acronym to remember when treating soft tissue injuries (SportEx Medicine, n.d.).

Reference List

SportEx Medicine. (no date) Promoting Health Through Exercise: OA OF THE KNEE. [online]. Available at: https://www.pennine-gp-training.co.uk/res/Physio%20OA%20of%20the%20knee.pdf. [Accessed on: 14 April 2021].